My build is almost the exact same as RababNoor's the only differences are that it has 4gb less of RAM, which would have a bit of an effect on performance, but you can always buy another 4gb of RAM for like £16 whenever you want. You don't need to buy it right away if you don't want to. The other difference is that it just barely goes over your budget, but I have the feeling you can throw another £8.42 at this build. Either of these builds would work just fine, but you're not gonna get anything better for the price, that's for sure.
PCPartPicker part list: 
http://uk.pcpartpicker.com/p/N42tGX
Price breakdown by merchant: http://uk.pcpartpicker.com/p/N42tGX/by_merchant/
CPU: AMD Athlon X4 860K 3.7GHz Quad-Core Processor  (£54.96 @ Aria PC) 
Motherboard: Gigabyte GA-F2A78M-D3H Micro ATX FM2+ Motherboard  (£45.40 @ Amazon UK) 
Memory: Kingston 4GB (1 x 4GB) DDR3-1600 Memory  (£16.23 @ Ebuyer) 
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  (£39.76 @ Amazon UK) 
Video Card: Gigabyte GeForce GTX 750 Ti 2GB Video Card  (£93.70 @ Ebuyer) 
Case: BitFenix Comrade ATX Mid Tower Case  (£28.43 @ CCL Computers) 
Power Supply: EVGA 430W 80+ Certified ATX Power Supply  (£29.94 @ CCL Computers) 
Total: £308.42
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-10-20 19:14 BST+0100