DEXTROMORGANERINO
Are you planning on overclocking? With a CPU cooler and motherboard of that quality, you should be able to and get some extra preformance for little to no power cost
Most of the stuff you're using looks really solid. I really like the Corsair 200R, as it's REALLY big and clean looking as well as actually being able to fit the monster 970. The corsair PSU's are some of the best on the market right now, and 8 gigs of memory should be more than enough. The 970 is a solid card, but it's really long/large, so people buying it should have a decent idea of if their case is big enough to house it (yours is). The intel i5, in my experience with mine, is a solid processor. If you wanted to go with a Third gen i5 to save some money, it wouldn't take that much of a toll on your performance (some of the big differences between the ivy bridge and haswell generations are optimization for tablets/laptops and better integrated graphics). However, if money isn't an issue, you should just stick with the 4th gen.
Also, it's a good idea to get both an SSD and a hard drive. The western digital is a solid drive, but if you want significantly better preformance for a <50£ difference, you should go with the Samsung 850 evo. The userbenchmark should pretty much explain it easily.
Your setup should be able to run both tf2 and cs:go at max framerate, with very little in terms of fluctuations. From what I've read (I have no experience with the 970 myself) it runs GTA at high/ultra settings just below 60 FPS, which means that you could easily bump it up to 75 or more with lower settings
I like your setup and I wish I had chosen the same stuff as you when I made my build