Well, he's not in the UK but I'd very strongly recommend Wayne Newberry. His web address is
http://home.ntelos.net/~nberry4/BerryStrings/index.htm
He makes a superb string at one of the best prices you'll find anywhere. His customer service is excellent.
I use his 16 strand Ultracam string on my 2005 Ultratech. It's very good. No creep, no peep rotation.
I suggest you take a look at his website and shoot him an e-mail.
You can also buy his trings through Centreshot in Malvern (if you're nervous about buying from the US) but they'll just do exactly what you'd do if you went direct.
Adam