Why did you drop down to a 270x? You said your budget was £1300 or less but that build is less than £800. That power supply is not good enough.
I'm not sure why you are wanting to stick with an AMD card when the GTX780 ot GTX780ti would be much better, but here you go
PCPartPicker part list:
http://uk.pcpartpicker.com/p/3rbxD
Price breakdown by merchant: http://uk.pcpartpicker.com/p/3rbxD/by_merchant/
Benchmarks: http://uk.pcpartpicker.com/p/3rbxD/benchmarks/
CPU: Intel Xeon E3-1230 V3 3.3GHz Quad-Core Processor (£179.99 @ Aria PC)
Motherboard: ASRock H87 Pro4 ATX LGA1150 Motherboard (£54.37 @ Amazon UK)
Memory: G.Skill Ares Series 8GB (2 x 4GB) DDR3-1600 Memory (£62.75 @ Amazon UK)
Storage: Crucial M500 120GB 2.5" Solid State Disk (£52.98 @ Amazon UK)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£34.80 @ Aria PC)
Video Card: XFX Radeon R9 290X 4GB Video Card (£369.99 @ Ebuyer)
Case: Corsair 300R ATX Mid Tower Case (£59.98 @ Dabs)
Power Supply: Antec EarthWatts Platinum 650W 80+ Platinum Certified ATX Power Supply (£85.31 @ Amazon UK)
Total: £900.17
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-04-13 22:39 BST+0100)