<form action="/Assisted/" method="post" id="assisted-form" accept-charset="UTF-8">
    <div>
        <div class="">
            FORM
        </div><div class="form-item form-type-textfield form-item-postcode">
            <label for="edit-postcode">Please enter your postcode </label>
            <input type="text" id="edit-postcode" name="postcode" value="" size="10" maxlength="10" class="form-text" />
        </div>
        <div class="form-item form-type-textfield form-item-street">
            <label for="edit-street">or your street </label>
            <input type="text" id="edit-street" name="street" value="" size="10" maxlength="50" class="form-text" />
        </div>
        <button id="edit-next" name="op" value="Search" type="button" class="form-submit" onclick="validatePostalCode()">Search</button>

        <div class="LoaderContainer"><div class="loaderMessage">Working...</div><div id="Loader" class="preloader"></div></div><input type="hidden" name="form_build_id" value="form-sdfgdfgdfgdfgdf " />
        <input type="hidden" name="form_id" value="assisted_form" />
    </div>
</form>

function validatePostalCode() {

var regExp = /^([Gg][Ii][Rr] 0[Aa]{2})|((([A-Za-z][0-9]{1,2})|(([A-Za-z][A-Ha-hJ-Yj-y][0-9]{1,2})|(([A-Za-z][0-9][A-Za-z])|([A-Za-z][A-Ha-hJ-Yj-y][0-9]?[A-Za-z])))) {0,1}[0-9][A-Za-z]{2})$/;
var postcode = document.forms["assisted-form"]["postcode"].value;

var form = document.forms["assisted-form"];
if (regExp.test(postcode)) {
    // Do something here, result is true.
    document.getElementById('edit-postcode').style.borderColor = "";
    $(".alert-box").hide();

    //below is testing


    $.ajax({
        url: '/Assisted/getAddresses?postcode=' +postcode,  //(rec)= Controller's-name
        //(recieveData) = Action's method name
        type: 'POST',
        timeout: '12000',
        datatype: 'text',
        data: {
            //Get the input from Document Object Model
            //by their ID
            postcode: form["postcode"].value,



        }

    });

    document.forms["assisted-form"].submit();

} else {

    toggler();

}

}
function toggler() {
var error = "Error";
$(".alert-box").show();
document.getElementById('edit-postcode').style.borderColor = "red";

}

public class AssistedController : Controller
{
   // string postcode = "";
    //string street = "";
    private static AddressList model = new AddressList();


    // GET: Assisted
    public ActionResult Index()
    {
        return View("Index", model);
    }


    public ActionResult getAddresses(string postcode)
    {
       // postcode = fc[0].ToString();

        EnviroWeb ew = new EnviroWeb();
        XmlNode xml = ew.GetAddress(", , , , " + postcode);
        foreach (XmlElement addressInfo in xml)
        {
            foreach (XmlElement teset in addressInfo["Addresses"])
            {
                model.listone.Add(new addressResults { FullAddress = teset["fulladdress"].InnerText });
            }
        }

       return View("Index", model);

    }

<div>

        @if (Model.listone.Count != 0)
    {
        <div>
            <select>
                @foreach (var test in Model.listone)
            {
                <option value="@test.FullAddress">@test.FullAddress</option>
        }
            </select>
        </div>


}
    </div>