IF you could stretch to £580 you could go with this:
PCPartPicker part list:
http://uk.pcpartpicker.com/p/290sc
Price breakdown by merchant: http://uk.pcpartpicker.com/p/290sc/by_merchant/
Benchmarks: http://uk.pcpartpicker.com/p/290sc/benchmarks/
CPU: AMD FX-6300 3.5GHz 6-Core Processor (£83.99 @ Aria PC)
Motherboard: Asus M5A97 R2.0 ATX AM3+ Motherboard (£59.00 @ Amazon UK)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1866 Memory (£69.98 @ Novatech)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£42.50 @ Aria PC)
Video Card: PowerColor Radeon HD 7850 2GB Video Card (£134.50 @ Ebuyer)
Case: Antec Three Hundred Two ATX Mid Tower Case (£54.99 @ Amazon UK)
Power Supply: Corsair CX 600W 80+ Bronze Certified Semi-Modular ATX Power Supply (£54.62 @ Amazon UK)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer (£13.18 @ Scan.co.uk)
Operating System: Microsoft Windows 8 (OEM) (64-bit) (£69.99 @ Ebuyer)
Total: £582.75
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-11-26 18:00 GMT+0000)
Actally I'd go with the one the guy above posted. However the wattage of the power supply is quite low and you won't be able to overclock much at all with the motherboard. But the GPU he suggested is much nicer.