Go for 2 x 8gb 2666Mhz RAM for ~£60 more. It's faster, and dual channel, either/both of which will help with some titles. Also 16gb can help in some games, and will improve the experience if you game and have browser tabs and other software open at the same time
Also swap the 860 Evo for an SSD from the M.2 SSD Drive menu. This will keep your 2.5" bay free to add either an SSD or HDD as an upgrade in the future.
Add and additional ram if there still a slot but mostly i would have slot for 2 RAM also this recommendation "Also swap the 860 Evo for an SSD from the M.2 SSD Drive menu. This will keep your 2.5" bay free to add either an SSD or HDD as an upgrade in the future. " would be the best also.