Ok shooting the middle of your budget if you need the stuff I mentioned before this should leave you some to play with
PCPartPicker part list:
http://uk.pcpartpicker.com/p/DgJcRB
Price breakdown by merchant: http://uk.pcpartpicker.com/p/DgJcRB/by_merchant/
CPU: Intel Core i5-4460 3.2GHz Quad-Core Processor (£127.19 @ Aria PC)
CPU Cooler: Zalman CNPS5X Performa CPU Cooler (£14.99 @ Novatech)
Motherboard: ASRock H87 Pro4 ATX LGA1150 Motherboard (£57.23 @ Amazon UK)
Memory: Kingston Black 8GB (2 x 4GB) DDR3-1600 Memory (£55.10 @ Amazon UK)
Storage: Mushkin Chronos 120GB 2.5" Solid State Drive (£43.19 @ Aria PC)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive (£38.70 @ Aria PC)
Video Card: Sapphire Radeon R9 270X 2GB Dual-X Video Card (£120.00 @ Amazon UK)
Case: Corsair Graphite Series 230T Black ATX Mid Tower Case (£53.76 @ CCL Computers)
Power Supply: Zalman 550W 80+ Gold Certified Semi-Modular ATX Power Supply (£48.91 @ Amazon UK)
Optical Drive: Lite-On iHAS124-04 DVD/CD Writer (£11.74 @ CCL Computers)
Total: £570.81
Prices include shipping, taxes, and discounts when available