The a8-3850 APU should retail for around $120 USD. The motherboard will cost about $110 USD. This will include 4 cores @ 2.9Ghz and an amd radeon 6550 video card, which is on par with the card you selected. If prices stay stable this is about 145 pounds, which should still leave you enough for the case, hard drive and power supply. Don't forget about the dvd drive though.
Faster memory makes Llano systems much happier so if you go this route you may want to purchase faster ram. I personally like corsair