any reasonable road bike with spds (or equivalent) and tribars attached then
personally i think you can get a perfectly good bike in the range £600 - £1,000, although i wouldn't spend less than that as you'll be itching to upgrade within 2 months
second hand can give good value
currently i'm on a trek 1500 that i really like, except i'm probably going to switch to bar end shifters (from simple bridged bolt-on tri bars)
it was slightly out of the price range above, but i bet i could have got the next model down and not noticed much of a difference