Thanks Steve, I'll try that, much appreciated.
EDIT: I have a strange problem now. I'm in
www.mysite.com/tomcat/admin, and I've made a change to home.tpl so that it displays a red bar across the top of the page, so that I can easily see which version of the site I am looking at. But when I go into 'General' and close the shop, it closes the real version of the shop, but not the test version! But I was definitely in
www.mysite.com/tomcat/admin/configuration.php when I ticked the box to close the shop.
I'm not sure how to create a separate database - is this easy to do?