if you ask in the customer service section really nicely 5UB could give you a quote for someone building a PC for you out of whatever bits you want, then posting it to you

(you may have to put the graphics card in yourself, but that would be the same with any prebuilt computer from OcUK)
i'm taking a guess here, but i expect the labour cost will increase the price by about 20%, so this is probably what i'd ask for:
Your basket
Product Name Qty Price Line Total
"Radon Torosaur" Intel Core i5 2500K 3.30GHz @ 4.40GHz Overclocked Bundle - Gigabyte £390.98
(£325.82) £390.98
(£325.82)
MSI ATI Radeon HD 6950 2048MB GDDR5 PCI-Express Graphics Card £199.98
(£166.65) £199.98
(£166.65)
Crucial RealSSD M4 128GB 2.5" SATA 6Gb/s Solid State Hard Drive £179.99
(£149.99) £179.99
(£149.99)
XFX 750W Black Edition Modular Power Supply £94.99
(£79.16) £94.99
(£79.16)
Coolermaster CM-690 II Advanced Dominator Case - Black £76.99
(£64.16) £76.99
(£64.16)
Seagate Barracuda 7200.12 500GB SATA 6Gb/s 16MB Cache - OEM (ST3500413AS) £30.98
(£25.82) £30.98
(£25.82)
Sony Optiarc AD-5260S 24x DVD±RW SATA ReWriter (Black) - OEM £15.98
(£13.32) £15.98
(£13.32)
Sub Total : £824.92
Shipping cost assumes delivery to UK Mainland with:
DPD Next Day Parcel
(This can be changed during checkout) Shipping : £12.50
VAT is being charged at 20.00% VAT : £167.48
Total : £1,004.90
since im not really sure how much money this will cost to build, if you have a bit to spare in your budget, i'd go for the 1TB version of the seagate 6GB/s hard drive