CPU: AMD A10-6800K 4.1GHz Quad-Core Processor (£104.39 @ Aria PC)
Motherboard: MSI FM2-A75MA-E35 Micro ATX FM2 Motherboard (£44.10 @ Scan.co.uk)
Memory: Corsair Vengeance LP 8GB (2 x 4GB) DDR3-2133 Memory (£53.49 @ Amazon UK)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£42.50 @ Aria PC)
Case: NZXT Tempest 210 ATX Mid Tower Case (£63.59 @ Overclockers.co.uk)
Power Supply: XFX ProSeries 450W 80+ Bronze Certified ATX Power Supply (£34.14 @ Scan.co.uk)
Total: £343.45
or(closer to budget)
CPU: AMD A8-6600K 3.9GHz Quad-Core Processor (£74.03 @ CCL Computers)
Motherboard: MSI FM2-A75MA-E35 Micro ATX FM2 Motherboard (£44.10 @ Scan.co.uk)
Memory: Corsair Vengeance LP 8GB (2 x 4GB) DDR3-2133 Memory (£53.49 @ Amazon UK)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive (£42.50 @ Aria PC)
Case: NZXT Tempest 210 ATX Mid Tower Case (£63.59 @ Overclockers.co.uk)
Power Supply: XFX ProSeries 450W 80+ Bronze Certified ATX Power Supply (£34.14 @ Scan.co.uk)
Total: £313.09
Something like this.