colr, .uk.com is not a valid extention - but .com is - so the site you mention is actually a subdomain of http://www.uk.com. If you go to that site you'll see a link to "register" one of these subdomains. It's pretty slick.

You can't move it to a new registrar, because you don't own a real domain name - and it seems pretty expensive, the ones I looked up were £65.00.