I can recommend re-cycle on Parkstone road ,,, erm hamilton I think (just outside Leicester)if your looking for second hand. I used to work there and he really is a top class bloke . I still go to him even now I'm living in Hull ... that's how much I rate him. (of course the ex-staff discount help's as well)
He does some brand new as well ... but I've never brought brand new from him so can't comment on his range.
Go in tell him what you want it for and he will help. he sometime's has some really good bikes in and they are ALWAYS sensibly priced.