Of course, check UK shops to see what those parts would cost in pounds rather than dollars. If you also need an OS though it's going to be a little tougher and you may need to drop the Video card to a 5770 and the CPU to an Athlon II X3 to allow for an OEM copy of Win 7
According to google £500 = $800 USD so I threw this together on newegg. This was done pretty quickly and I really didn't shop around for prices so I'm sure there is room for improvement. I hope this gives you a decent starting point.
Again, I didn't spend a lot of time on this and there's probably a much better budget build out there but I hope it gets you started. If you're not interested in OCing you could easily drop the heatsink and perhaps go to a less expensive CPU or AMD chip. The money you save there could also get you a nicer GPU. It really depends on what you're wanting to do