Pilot 16,
Sorry, I can't point you to a specific U.K. website, but as Tinstaafl says, retailers carrying LED lights are not very difficult to find.
This is one place that sells the 1930 L1 by mailorder:
http://www.southwestpublicsafety.com/pel19l1led.html
This is the Photon of which Tinstaafl speaks:
http://www.equipped.org/led_lights3b.htm It got a great review from "Equipped to Survive". They were slightly less keen on the 1930 L1, but were still very complementary:
http://www.equipped.org/led_lights4.htm
MLS-12D
P.S.: you will find the following two articles to be of general interest:
http://www.equipped.org/led_lights.htm
http://www.equipped.org/devices27.htm