Hi I don't play games on my PC but you could ask such as
click here what they would advise for a balanced gaming PC for the amount you are prepared to pay and to include VAT and delivery.
There is a contact at the base of the screen and a choice of email addresses to send your query to. you can say what processor you prefer if you want Intel or AMD and they will do the rest.
If you scroll down the pages to build a PC you can also chose which Case you would like to be included in the price.