I agree with aJohnson. The weak pound has destroyed the bike industry a little and the bargains on new bikes that could be had this time last year don't exist. Brand new at £400-£500 you'd be very lucky to get a carbon fork and Sora groupset on a basic alu frame even if you got a good deal on an 09 bike. Nothing wrong with that of course, I spent the first 3 years of my road biking on such a machine and loved every second of it and if that's the route you'd prefer to take I'm sure I've a few suggestions.
But, there's never been a better time to buy second hand. For instance, someone on another forum I frequent picked up a Carrera Virago off
ebay recently. Carbon frame and fork, a mix of Dura Ace and Ultegra with about 100 miles on the clock for £550! A bit over your budget and bargains like that don't come about often, but a few weeks spent searching ebay or gumtree will come up with a few gems just like that within your budget every now and then.
