www.jantzsupply.com
www.kovalknives.com
www.texasknife.com
www.knifeandgun.com
If the value of an order is below £18 you can order without being hit for duty. At least, wny I last ordered from Jantz I didn't get hit.
I am guessing that you aren't ready to dive into heat treating yet, but that shouldn't stop you from making your own blade from O-1 steel (available from a number of places). There are several helpful souls over on BB who could probably be prevailed upon to treat a blade for you.
You can get some pretty good Kellam blades from Stuart.
Best advice. Go buy a book. Wayne Goddard's are very good as is the Barney and Loveless "How to make Knives"
There are also good tutorials around the net. Terry Primos has a couple of great ones, guards and mortised tangs. The Engnath site has a ton of info.
What sort of knife are you aiming for, or do you just want something to devour all your spare time