Absolutely fantastic computer for its cost. I chose to upgrade the processor, add the GTX 660 graphics card and increase the RAM to 8 GB (Came to under £800 I believe) and it has run everything I have thrown at it at the highest possible settings. Impressively it runs Tomb Raider (2013) maxed out very smoothly with little framerate drop. As my first proper gaming PC this is everything I hoped it would be and it proves that you don't have to spend twice this amount to play games at their best.
As for the service, UKGC informed me regularly about the changing status of my order and the delivery time was as expected with no problems. I was recommended UKGC by a friend and I wouldn't hesitate to recommend it to others. Overall, I am very happy with my new PC!