Ok, firstly thanks for all the help, and secondly apologies for the going backwards and forwards. I appreciate the patience whilst I try and learn.
I'm set on the below and will be ordering today, I think i needed to do more research before I asked for your guys time.
CPU: AMD FX-6300 3.5GHz 6-Core Processor
Motherboard: Asus M5A78L-M/USB3 Micro ATX AM3+ Motherboard
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1600 Memory
Storage: Kingston SSDNow V300 Series 120GB 2.5" Solid State Disk
Video Card: Sapphire Radeon HD 7850 1GB Video Card
Case: Aerocool DS Cube Black Edition Silent Cube MicroATX Mini Tower Case
Power Supply: Corsair RM 550W 80+ Gold Certified Fully-Modular ATX Power Supply
This comes in at £503, and I've managed to sneak the SSD in for that.
I couldn't see a huge amount of difference between the 7850 and the 7870 in my research, so for £40 less the 7850 seemed to make sense.
I went mATX in the end as I fancy a smaller build. I got a Pioneer BDR-208EBK for Xmas, so Bluray I'm covered.
Thanks again