I've just helped my sister buy a gaming PC for my nephew - eventually we went with one from the Dell Outlet Store:
https://outlet.euro.dell.com/Online/...j5V9%2bQ9WE%3d
Prices don't include VAT but never pay full price - if you know anyone who is NHS/student/military/etc they can get a 15% discount. I think they're excellent value - as an example, if you were a self-builder, the price of the individual parts on this one would set you back over £850. With a 15% discount applied it's £765:
https://outlet.euro.dell.com/Online/...j%2bvZ%2f4AQmh
Also, keep an eye on hotukdeals.com:
https://www.hotukdeals.com/tag/gaming-pc
Avoid the packages and buy a monitor seperately - for gaming make sure you get one with a decent refresh rate and response time.