You could try Kerso. I think he does the regular PWs, although they are the US spec ones (I think) and I guess technically illegal frequency for UK. But if you don't mind distrupting the local emergency services and aeroplanes crashing all around you, I guess they're fine.
The new Canon eTTL PWs are not without their problems - RF interference from the guns themselves cutting range. There's plenty about it on the PW site, and their rather unsatisfactory suggested solutions. Release of the Nikon iTTL version has been delayed, I'm not sure if that is related. If you want E-TTL, also consider Radio Poppers - not such a neat solution, but they do work and I think are cheaper, if you can get hold of them.