Building off the already suggested builds, I changed it to a Xeon since I have a feeling OP isn't looking to mess with OC and the extra Hyperthreading could instead come in handy. Yes it's a Z series motherboard but they're priced so closely to the H and B series I just chucked it in.
PCPartPicker part list:
http://uk.pcpartpicker.com/p/37ncg
Price breakdown by merchant: http://uk.pcpartpicker.com/p/37ncg/by_merchant/
Benchmarks: http://uk.pcpartpicker.com/p/37ncg/benchmarks/
CPU: Intel Xeon E3-1230 V2 3.3GHz Quad-Core Processor (£169.62 @ Scan.co.uk)
Motherboard: ASRock Z77 Pro3 ATX LGA1155 Motherboard (£63.48 @ Ebuyer)
Memory: G.Skill Sniper Series 8GB (2 x 4GB) DDR3-1866 Memory (£68.81 @ Amazon UK)
Storage: Samsung 840 EVO 120GB 2.5" Solid State Disk (£62.99 @ Amazon UK)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£35.99 @ Aria PC)
Video Card: Asus GeForce GTX 770 2GB Video Card (£242.90 @ Amazon UK)
Case: Xigmatek MIDGARD II (Black) ATX Mid Tower Case (£47.68 @ Amazon UK)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply (£44.98 @ Amazon UK)
Optical Drive: Samsung SH-224DB/BEBE DVD/CD Writer (£11.78 @ CCL Computers)
Total: £748.23
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-03-10 14:09 GMT+0000)
Also Matt gibbi don't worry, assembling it yourself is simple and you'll save quite a lot of money in the process. There are various guides all over the internet to assist you; it's like lego for adults.