Añadir códigos postales a un formulario hecho con Divi posiblemente conectado a un Api

Hola, necesitamos ayuda de alguien para añadir los códigos postales de ciudades de Londres a un formulario en el siguiente link: https://sotosolutions.co.uk/find-a-boiler/ deben pulsar en Start Now > Gas > y seguir todas las opciones como deseen marcando Yes donde lo pregunte, al final aparecerá un campo de añadir Codigo postal, esos códigos postales son los que hay que vincular, no hay bases de datos, al parecer estaba consultando una API, este es el js del formulario:

var house_details = {};
var current_step = "#start-section";

function ScrollToTop(){
    if (navigator.userAgent.match(/(iPod|iPhone|iPad|Android)/)) {         
            window.scrollTo(0,200) // first value for left offset, second value for top offset

        }
}

function CheckPostCode(){
    jQuery('#PostcodeError').hide();
    jQuery('#PostCodeNotServicedError').hide();
        
      var postcode = jQuery('#postcode_textbox').val();
     
      if(postcode == ""){
          jQuery('#PostcodeError').show();
      }
     
      else{
          
          var filtered_postcode = postcode.replace(/\s/g, '').toUpperCase();
          
          house_details["filtered_postcode"] = filtered_postcode;
          Cookies.set('postcode', filtered_postcode);
          
            var region = null;
          jQuery.ajax("https://api.postcodes.io/postcodes/" + filtered_postcode)
        .done(function(data) {
            region = data.result.region;
            CheckValidRegion(region);
        })
        .fail(function() {
            jQuery('#PostcodeError').show();
        });
       
    }
}

function CheckValidRegion(region){
    if(region == "South East"){
        
        var querystring = "https://www.sotosolutions.co.uk/boilers/";
        
        var boiler_type = "";
        
        if (house_details["boiler_type"] == "combi-boiler"){
            boiler_type = "combi-boiler";
        }
        else if (house_details["boiler_type"] == "system-boiler"){
            boiler_type = "system-boiler";
        }
        else if (house_details["boiler_type"] == "conventional-boiler"){
            boiler_type = "conventional-boiler";
        }
        
        if ("convert_combi" in house_details){
            
            if (house_details["convert_combi"] == "yes"){
                boiler_type = "combi-boiler";
            }
        }
        
        var convertcombi = "";
        var convertfromconventional = "";        

        //If already a combi, then don't add convert
        if (house_details["boiler_type"] == "combi-boiler"){
            convertcombi = "0";
        }
        //Else if final convert type is combi-boiler, but not originally, then set convert flag to 1
        else {
                if (boiler_type == "combi-boiler"){
                    convertcombi = "1";
                
                    //Now also check if from conventional boiler so need to add extra tag
                    if (house_details["boiler_type"] == "conventional-boiler"){
                        convertfromconventional = "1";
                    }
                }
                else {
                    convertcombi = "0";
                }
        }
        
        var newboilerlocation = 0;
        
        if ( house_details["newboilersameplace"] == "no" ){
            newboilerlocation = house_details["newboilerlocation"];
        }
        
        var bedroom = house_details["bedroom"].replace("bedrooms-", "");
        var bathroom = house_details["bathroom"].replace("bathrooms-", "");
        
        var roof = house_details["flue_on"] == "roof" ? 1 : 0;
        
        var filtered_postcode = house_details["filtered_postcode"];
        
        var filter = "?filter_bd=" + bedroom + "&filter_bth=" + bathroom + "&convertcombi=" + convertcombi + "&roof=" + roof + "&newboilerlocation=" + newboilerlocation;
        
        if (convertfromconventional == "1") {
            filter += "&convertfromconventional=" + convertfromconventional;
        }

        querystring = querystring + boiler_type + "/" + filter;
        
        var smartlook = "https://sotosolutions.co.uk/survey/SmartLook.php" + filter + "&postcode=" + filtered_postcode;
                
        jQuery.ajax(smartlook)
        .done(function(data) {
            
        });
        
        window.location.href=querystring;
        
    }
    else{
        jQuery('#PostCodeNotServicedError').show();
    }
}

jQuery(document).ready(function() {
                        
    jQuery(document).on('click','#bq-start',function(e){
        e.preventDefault();
        jQuery('#start-section').hide();
        
        jQuery('#step-fuel-type').data('backstep', '#start-section');
        current_step = "#step-fuel-type";
        jQuery('#step-fuel-type').show();
        
        jQuery('.backbutton').show();
        ScrollToTop();
   
    });
    
        jQuery('.fuel-kind').on('click',function(e){
            
        e.preventDefault();
        
      jQuery('.fuel-kind').removeClass('active');
        jQuery(this).addClass('active');
        
        var fuel_type_selected = this.id;
        
        if (typeof fuel_type_selected != 'undefined'){
            
            house_details["fuel_type"] = fuel_type_selected;
            Cookies.set('fuel_type', fuel_type_selected);
            
            jQuery('#step-fuel-type').hide();
            
            if (fuel_type_selected == 'gas'){
                jQuery('#step-gas-boiler-type').data('backstep', '#step-fuel-type');
                current_step = "#step-gas-boiler-type";
                jQuery('#step-gas-boiler-type').show();
            }
            else{
                jQuery('#step-give-ring').data('backstep', '#step-fuel-type');
                current_step = "#step-give-ring";
                jQuery('#step-give-ring').show();
            }
        }                
        
        ScrollToTop();
        
    });
    
    jQuery('.boiler-kind').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.boiler-kind').removeClass('active');
        jQuery(this).addClass('active');
        
        var boiler_type_selected = this.id;
            
        
        if(typeof boiler_type_selected != 'undefined'){
            
            house_details["boiler_type"] = boiler_type_selected;
            Cookies.set('boiler_type', boiler_type_selected);
            
            jQuery('#step-gas-boiler-type').hide();
            
            if(boiler_type_selected == "combi-boiler"){
                jQuery('#step-current-boiler-location').data('backstep', '#step-gas-boiler-type');
                current_step = "#step-current-boiler-location";
                jQuery('#step-current-boiler-location').show();
            }else{
                jQuery('#step-convert-combi').data('backstep', '#step-gas-boiler-type');
                current_step = "#step-convert-combi";
                jQuery('#step-convert-combi').show();    
            }    
        }
        
        ScrollToTop();
        
    });
    
    jQuery('.convert-combi').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.convert-combi').removeClass('active');
        jQuery(this).addClass('active');
        
        var convert_combi = this.id;
            
        
        if(typeof convert_combi != 'undefined'){
            
            house_details["convert_combi"] = convert_combi;
            Cookies.set('convert_combi', convert_combi);
            
            jQuery('#step-convert-combi').hide();
            
            if(convert_combi == "yes"){
                jQuery('#step-cold-tap').data('backstep', '#step-convert-combi');
                current_step = "#step-cold-tap";
                jQuery('#step-cold-tap').show();
            }else{
                if(house_details["boiler_type"] == "back-boiler"){
                    jQuery('#step-give-ring').data('backstep', '#step-convert-combi');
                    current_step = "#step-give-ring";
                    jQuery('#step-give-ring').show();
                }
                else{
                    jQuery('#step-current-boiler-location').data('backstep', '#step-convert-combi');
                    current_step = "#step-current-boiler-location";
                    jQuery('#step-current-boiler-location').show();    
                }
            }    
        }
        
        ScrollToTop();
        
    });
    
    jQuery('.cold-tap').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.cold-tap').removeClass('active');
        jQuery(this).addClass('active');
        
        var coldtap = this.id;
            
        
        if(typeof coldtap != 'undefined'){
            
            house_details["coldtap"] = coldtap;
            Cookies.set('coldtap', coldtap);
            
            jQuery('#step-cold-tap').hide();
            
            if(coldtap != "slow"){
                jQuery('#step-current-boiler-location').data('backstep', '#step-cold-tap');
                current_step = "#step-current-boiler-location";
                jQuery('#step-current-boiler-location').show();
            }else{
                jQuery('#step-give-ring').data('backstep', '#step-cold-tap');
                current_step = "#step-give-ring";
                jQuery('#step-give-ring').show();
            }    
        }
        
        ScrollToTop();
        
    });
    
    jQuery('.current-boiler-location').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.current-boiler-location').removeClass('active');
        jQuery(this).addClass('active');
        
        var currentboilerlocation = this.id;
            
        if(typeof currentboilerlocation != 'undefined'){
            
            house_details["currentboilerlocation"] = currentboilerlocation;
            Cookies.set('currentboilerlocation', currentboilerlocation);
            
            jQuery('#step-current-boiler-location').hide();
            
            jQuery('#step-new-boiler-same-place').data('backstep', '#step-current-boiler-location');
            current_step = "#step-new-boiler-same-place";
                
            jQuery('#step-new-boiler-same-place').show();
            
        }
        ScrollToTop();
        
    });
    
    jQuery('.new-boiler-same-place').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.new-boiler-same-place').removeClass('active');
        jQuery(this).addClass('active');
        
        var newboilersameplace = this.id;
                    
        if(typeof newboilersameplace != 'undefined'){
            
            if(newboilersameplace == 'new-boiler-yes'){
                newboilersameplace = 'yes';
            }
            else{
                newboilersameplace = 'no';
            }
            
            house_details["newboilersameplace"] = newboilersameplace;
            Cookies.set('newboilersameplace', newboilersameplace);
            
            jQuery('#step-new-boiler-same-place').hide();
            
            if(newboilersameplace == "yes"){
                jQuery('#step-home-type').data('backstep', '#step-new-boiler-same-place');
                current_step = "#step-home-type";
                jQuery('#step-home-type').show();
            }else{
                jQuery('#step-is-outside-wall').data('backstep', '#step-new-boiler-same-place');
                current_step = "#step-is-outside-wall";
                jQuery('#step-is-outside-wall').show();
            }    
            
        }
        
        ScrollToTop();
        
    });
    
    jQuery('.is-outside-wall').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.is-outside-wall').removeClass('active');
        jQuery(this).addClass('active');
        
        var isoutsidewall = this.id;
            
        if(typeof isoutsidewall != 'undefined'){
            
            house_details["isoutsidewall"] = isoutsidewall;
            Cookies.set('isoutsidewall', isoutsidewall);
            
            jQuery('#step-is-outside-wall').hide();
            
            if(isoutsidewall == "outside-wall-yes"){
            
                jQuery('#step-new-boiler-location').data('backstep', '#step-is-outside-wall');
                current_step = "#step-new-boiler-location";
                
                //Change data of current location:
                //var current_location_id = house_details["currentboilerlocation"];
                
                //jQuery('#step-new-boiler-location ' + '#' + current_location_id).hide();
                //jQuery('#step-new-boiler-location ' + '#' + current_location_id).attr("id", "same-room");
                //jQuery('#step-new-boiler-location ' + '#same-room span.et_pb_image_wrap img').attr("src", "https://www.sotosolutions.co.uk/wp-content/uploads/same-room.png");
                //jQuery('#step-new-boiler-location ' + '#same-room h1.et_pb_module_header').text("Same Room");
                
                    
                jQuery('#step-new-boiler-location').show();
            }
            else{
                jQuery('#step-give-ring').data('backstep', '#step-is-outside-wall');
                current_step = "#step-give-ring";
                jQuery('#step-give-ring').show();
            }
            
        }
        ScrollToTop();
        
    });
    
    jQuery('.new-boiler-location').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.new-boiler-location').removeClass('active');
        jQuery(this).addClass('active');
        
        var newboilerlocation = this.id;
            
        if(typeof newboilerlocation != 'undefined'){
            
            house_details["newboilerlocation"] = newboilerlocation;
            Cookies.set('newboilerlocation', newboilerlocation);
            
            jQuery('#step-new-boiler-location').hide();
            
            if(newboilerlocation != "other"){
            
                jQuery('#step-home-type').data('backstep', '#step-new-boiler-location');
                current_step = "#step-home-type";
                    
                jQuery('#step-home-type').show();
            }
            else{
                jQuery('#step-give-ring').data('backstep', '#step-new-boiler-location');
                current_step = "#step-give-ring";
                jQuery('#step-give-ring').show();
            }
            
        }
        ScrollToTop();
        
    });
    
    jQuery('.home-kind').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.home-kind').removeClass('active');
        jQuery(this).addClass('active');
        
        var homekind = this.id;
            
        if(typeof homekind != 'undefined'){
            
            house_details["homekind"] = homekind;
            Cookies.set('homekind', homekind);
            
            jQuery('#step-home-type').hide();
            
            jQuery('#step-bedrooms').data('backstep', '#step-home-type');
            current_step = "#step-bedrooms";
                
            jQuery('#step-bedrooms').show();
            
        }
        
        ScrollToTop();
        
    });    
    
    jQuery('.bedroom-number').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.bedroom-number').removeClass('active');
        jQuery(this).addClass('active');
        
        var bedroom_number = this.id;
            
        if(typeof bedroom_number != 'undefined'){
            
            house_details["bedroom"] = bedroom_number;
            Cookies.set('bedroom', bedroom_number);
            
            jQuery('#step-bedrooms').hide();
            
            jQuery('#step-bathrooms').data('backstep', '#step-bedrooms');
            current_step = "#step-bathrooms";
            
            jQuery('#step-bathrooms').show();
            
        }
        
        ScrollToTop();
        
    });    
    
    jQuery('.bathroom-number').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.bathroom-number').removeClass('active');
        jQuery(this).addClass('active');
        
        var bathroom_number = this.id;
            
        if(typeof bathroom_number != 'undefined'){
            
            house_details["bathroom"] = bathroom_number;
            Cookies.set('bathroom', bathroom_number);
            
            jQuery('#step-bathrooms').hide();
            
            jQuery('#step-flue-on').data('backstep', '#step-bathrooms');
            current_step = "#step-flue-on";
            
            jQuery('#step-flue-on').show();
            
        }
        
        ScrollToTop();
        
    });    
    
    jQuery('.flue-on').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.flue-on').removeClass('active');
        jQuery(this).addClass('active');
        
        var flue_on = this.id;
            
        if(typeof flue_on != 'undefined'){
            
            house_details["flue_on"] = flue_on;
            Cookies.set('flue_on', flue_on);
            
            jQuery('#step-flue-on').hide();
            
            if(flue_on == 'roof'){
                jQuery('#step-roof-type').data('backstep', '#step-flue-on');
                current_step = "#step-roof-type";
                jQuery('#step-roof-type').show();
            }
            else{
                jQuery('#step-enter-postcode').data('backstep', '#step-flue-on');
                current_step = "#step-enter-postcode";
                jQuery('#step-enter-postcode').show();
            }
        }
        
        ScrollToTop();
        
    });    
    
    jQuery('.roof-type').on('click',function(e){
        
        e.preventDefault();
        
      jQuery('.roof-type').removeClass('active');
        jQuery(this).addClass('active');
        
        var roof_type = this.id;
            
        if(typeof roof_type != 'undefined'){
            
            house_details["roof_type"] = roof_type;
            Cookies.set('roof_type', roof_type);
            
            jQuery('#step-roof-type').hide();
            jQuery('#step-enter-postcode').data('backstep', '#step-roof-type');
                current_step = "#step-enter-postcode";
            jQuery('#step-enter-postcode').show();
            
        }
        
        ScrollToTop();
        
    });    
    
    jQuery('.postcode_button').on('click',function(e){
        
        e.preventDefault();
        
        CheckPostCode();
        
        ScrollToTop();
        
    });
    
    jQuery('#postcode_form').on('submit',function(e){
        
        e.preventDefault();
                
        CheckPostCode();
        
        ScrollToTop();
        
    });
    
    jQuery('.backbuttonicon').on('click', function(e){
        
        e.preventDefault();
        
        var backstep = jQuery(current_step).data('backstep');
        
        if(backstep == "#start-section"){
            jQuery(".backbutton").hide();
        }
        
        jQuery(current_step).hide();
        current_step = backstep;
        jQuery(backstep).show();

    });
 
});
    


Saludos.