Catergory and Tag dropdown menu search function

Hi all,

I’m starting a nights out listing site on wordpress and I’ve got it set up so the categories are the venues (Restaurants, Pubs, Clubs etc) and the tags are the locations (London, Birmingham etc) and basically I want to create a search function in the sidebar so the user can select that they are looking for Pubs in London.

I’ve managed to get the categories working using the code available on the codex (see code below)

<h3>Search</h3>
		<form action="<?php bloginfo('url'); ?>" method="get">
        <div>
        <?php wp_dropdown_categories('hierarchical=2'); ?>
        <input type="submit" name="submit" value="Search" />
        </div>
        </form>

I just need to add a tag dropdown to that, can anyone help me?