upgrade to I5 4210M, 8GB of RAM, and gtx 850M.
add a 7200RPM harddrive, and if you can afford it some extra thermal paste.
the gtx 850M upgrade is completely free.
If you want to save some more money, if you have a spare operating system disk, you can take off the OS and get an I7 and an upgraded wireless card (connects to your internet) or even have a 1080p screen.
the gtx 850M has the same capabilities of the gtx 765M.
Game benchmarks can be found here: http://www.notebookcheck.net/NVIDIA-....107795.0.html
however please note that 720p (your max screen resolution) comes under the "high" settings on those benchmarks, not ultra.
this will play watchdogs at 720p max @ 51.2fps. That's just for example.
titanfall and battlefield 4 get between 58-64 fps at their max settings at 720p
Guaranteed best bang for the buck in Britain at this price range.
Hope this helps.
(I'm on the Toms hardware forum a lot)
Edit: (have actually read everything above now) the hybrid drive will do so little that it's not worth it all, if you've got a few pounds to spare, I would suggest adding extra thermal paste (£9), the silver warranty (£5) and an upgraded intel wireless card "ac 7260" (about £15-20) all are well worthwhile upgrades
if you've still got spare cash, add an a small SSD for the OS and your favourite games.