I know Millet is a pain in the arse to get in the UK. I got my Millet B3s from Adventurepeaks in ambleside. I have also contacted them to see if they can get them on order as they have the matching jacket.
In reply to Milesy:
do you not think that walking in comfortably wearing the same clothes you'll climb in including water proofs is a bit optimistic? If it was me I think even with the vents open on the upper part of my leg I'll typically end up very sweaty before I start climbing (either that or I'd have to basically unzip my entire legs), and of course getting sweaty only leads to one thing on the next belay.