The definitive OTP ( Off-The-Peg ) List (<£500 and <£1,000 sections)

It seemed you want a bike purely to commute with, try and test out the Ridgeback Genesis Flyer, Specialized Langster, and probably the Lemond Fillmore** as they're within your price range and are decent bike.
**

Thanks for the tips, Ed. I've actually looked at those bikes, but i forgot to add that i prefer flat bars to drop bars. In fact, I'd probably look into getting narrow courier-style bars, if the Giant or Trek have bars that are too wide.