drop them an email or phone Steve direct there the best for cocker parts in the UK, just because its not on the web site doesn't mean they dint have it ^^
Aye, you can buy amazing pump kits from CCM (Chipley custom machine). They have a great reputation, and one that stands with their flagship marker, the S6
Unfortunately, they are an American company, so you have to import. www.chipleymachine.com
Edit
I couldn't find a pic of the trilly with the CCM kit, maybe i was wrong about the kits. Anyway, here are some pics for you.
a trilogy with a Wevopaintball.com kit (just a reseller of the WGP kit):