Edit in JSFiddle

  var key = '1234567890123456789012345678901234567890';
  var version = '1';
  $("input[name='address[postcode]']").postcodeProvider({
    post_town: $("input[name='address[town]']"),
    building_name: $("input[name='address[buildingName]']"),
    building_number: $("input[name='address[buildingNumber]']"),
    thoroughfare_and_descriptor: $("input[name='address[street]']"),
    country: $("select[name='address[country]']"),
    county: $("input[name='address[county]']"),
    locality: $("input[name='address[locality]']")
  }, key, version);
<div class="container">
  <form name="address" method="post">
    <div class="row">
      <div class="col-xs-12 col-sm-6">
        <div class="form-group">
          <label class="control-label" for="address_postcode">Postcode</label>
          <input type="text" id="address_postcode" name="address[postcode]" class="force-uppercase form-control" />
        </div>
      </div>
    </div>
    <div class="row">
      <div class="col-xs-12 col-sm-6">
        <div class="form-group">
          <label class="control-label" for="address_buildingNumber">Building Number</label>
          <input type="text" id="address_buildingNumber" name="address[buildingNumber]" class="form-control" />
        </div>
      </div>
      <div class="col-xs-12 col-sm-6">
        <div class="form-group">
          <label class="control-label" for="address_buildingName">Building Name</label>
          <input type="text" id="address_buildingName" name="address[buildingName]" class="form-control" />
        </div>
      </div>
    </div>
    <div class="row">
      <div class="col-xs-12 col-sm-6">
        <div class="form-group">
          <label class="control-label required" for="address_street">Street</label>
          <input type="text" id="address_street" name="address[street]" required="required" class="form-control" />
        </div>
      </div>
      <div class="col-xs-12 col-sm-6">
        <div class="form-group">
          <label class="control-label required" for="address_town">Town</label>
          <input type="text" id="address_town" name="address[town]" required="required" class="form-control" />
        </div>
      </div>
    </div>
    <div class="row">
      <div class="col-xs-12 col-sm-6">
        <div class="form-group">
          <label class="control-label required" for="address_county">County</label>
          <input type="text" id="address_county" name="address[county]" required="required" class="form-control" />
        </div>
      </div>
      <div class="col-xs-12 col-sm-6">
        <div class="form-group">
          <label class="control-label required" for="address_country">Country</label>
          <select id="address_country" name="address[country]" required="required" class="form-control">
            <option value="" selected="selected">choose</option>
            <option value="England">England</option>
            <option value="Scotland">Scotland</option>
            <option value="Wales">Wales</option>
            <option value="Northern Ireland">Northern Ireland</option>
          </select>
        </div>
      </div>
    </div>
    <div class="row">
      <div class="col-xs-12">
        <div class="form-group">
          <button type="submit" id="address_submit" name="address[submit]" class="btn btn-primary btn">Submit</button>
        </div>
      </div>
    </div>
  </form>
</div>