Try this build:
Intel i7-3770k £248.89@http://www.amazon.co.uk/Intel-Generation-i7-3770K-3-50GHz-Technology/dp/B007X1JM30/ref=sr_1_1?s=computers&ie=UTF8&qid=1363724550&sr=1-1
Asus SABERTOOTH Z77 Motherboard £175.99@http://www.amazon.co.uk/Asus-SABERTOOTH-Motherboard-CrossfireX-Supports/dp/B007KZQEHQ/ref=sr_1_1?s=computers&ie=UTF8&qid=1363724684&sr=1-1
Noctua NH-D14 £64.95@http://www.amazon.co.uk/Noctua-NH-D14/dp/B0042ZIPR4
Corsair 16 GB Vengeance £90.98@http://www.amazon.co.uk/Corsair-Vengeance-240-pin-DDR3-RAM-Memory/dp/B006EWUO22/ref=pd_cp_computers_2
Asus Nvidia GeForce 2GB GTX 680 DirectCU II OC Graphics Card £399.99@http://www.amazon.co.uk/Asus-Nvidia-GeForce-DirectCU-Graphics/dp/B007X8ENIW/ref=sr_1_1?s=computers&ie=UTF8&qid=1363735583&sr=1-1
Seagate 750GB Momentus XT Serial 2.5 inch 7200 RPM SSD/HDD Hybrid £90.40@http://www.amazon.co.uk/Seagate-750GB-Momentus-Serial-Hybrid/dp/B0068QO82G/ref=sr_1_1?s=computers&ie=UTF8&qid=1363725100&sr=1-1
Sony AD-7280S-0B 24x Internal SATA DVD Multi Writer £20.66@http://www.amazon.co.uk/Sony-AD-7280S-0B-Internal-Multi-Writer/dp/B0057FRTPW/ref=sr_1_cc_1?s=aps&ie=UTF8&qid=1363725259&sr=1-1-catcorr
Corsair Carbide 500R £95.98@http://www.amazon.co.uk/Corsair-Carbide-microATX-Tower-Black/dp/B005E983JW/ref=sr_1_1?s=computers&ie=UTF8&qid=1363726200&sr=1-1
Seasonic 650W M12II Bronze Series Modular Power Supply (Ample +12V Outputs, Smart and Silent Fan Control, Multi-GPU Technologies Supported) £96.20@http://www.amazon.co.uk/Seasonic-Modular-Multi-GPU-Technologies-Supported/dp/B00607JMI8/ref=sr_1_2?s=computers&ie=UTF8&qid=1363736932&sr=1-2
It totals to £1295.43, and the shipping for all the parts are free.
Don't worry about the hard drive being 2.5", the case has tool-less hard drive racks with 2.5" capability. Also, the 8gb flash memory will contain the operating system, making your computer boot time faster and some programs that get stored there.