POSTCODE: <input type="text" name="adv_postcode" id="adv_postcode" class="addressfields"/>

<script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyAJcNfHosSZtteJp9jndsH8pJ4YZlBMHTA&libraries=places&sensor=false&callback=initialize"  async defer >

function initialize() {
    $('#adv_postcode').each(function () {
        initialize2(this);
    });
}
function initialize2(elementID) {
    var options = {
        componentRestrictions: {
            country: 'uk'
        }
    };
    var autocomplete_element = new google.maps.places.Autocomplete(elementID, options);

    autocomplete_element.addListener('place_changed', function () {
        elementID.value = fillInAddress(autocomplete_element);
    });
}