$(document).ready(function () {
    $('#txtSearchTerm').autocomplete({
        source: function (request, response) {
            $.ajax({
                url: "http://www.cks.nhs.uk/UserControls/Search/AutoSuggest.ashx?term=" + $('#txtSearchTerm').val(),
                dataType: "xml",
                success: function (xml) {
                    var data = xml;
                    var availableSearchedTerms = new Array();

                    //process response  

                    $(xml).find('term').each(function () {
                        var Term = $(this).text();
                        availableSearchedTerms.push(Term);
                    });

                    response(availableSearchedTerms);

                }
            });
        },
        minLength: 3
    });
});