Will I encounter any problems building this pc ?

dottorrent

Honorable
IMHO, the Core i3s are just not good enough any more. More people use AMD's FX 6300 as opposed to the Core i3 now, thanks to the amazing value you get with it. Secondly, Casecom cases, even their high end ones, are terrible. They use thin metal which can deform easily with tight screws and heat. Plus, don't get an OEM copy of windows 7. The key ties with the serial numbers of your components. If you were to upgrade or replace a broken component, you won't get the updates any more. Here is a slightly better build for around your budget -

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: AMD FX-6300 3.5GHz 6-Core Processor (£83.99 @ Aria PC)
CPU Cooler: Cooler Master Hyper 212 EVO 82.9 CFM Sleeve Bearing CPU Cooler (£23.98 @ Scan.co.uk)
Motherboard: Gigabyte GA-78LMT-USB3 Micro ATX AM3+ Motherboard (£37.57 @ Aria PC)
Memory: PNY XLR8 8GB (2 x 4GB) DDR3-1600 Memory (£38.31 @ Amazon UK)
Storage: Western Digital Caviar Green 1TB 3.5" 5400RPM Internal Hard Drive (£44.80 @ CCL Computers)
Case: NZXT Source 210 Elite (Black) ATX Mid Tower Case (£38.65 @ Scan.co.uk)
Power Supply: XFX 550W 80+ Bronze Certified ATX Power Supply (£48.99 @ Amazon UK)
Operating System: Microsoft Windows 8.1 - OEM (64-bit) (£69.32 @ CCL Computers)
Other: MSI Radeon HD 7850 OC 2GB (£89.99)
Total: £475.60
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-12-01 13:26 GMT+0000)

Honestly, the FX 6300 is a better CPU. It overclocks well and is faster.