Hey there buddy, I personally have a 270x, plays most games at good settings, when gaming, the most major factor to FPS is the GPU more than the CPU side, However, you will want a half decent CPU, i would say the 6300 (great budget gaming CPU) + 270x (not much difference to the 270 but meh) If you cna pick up a 270 non X for £30 -£40 les you might as well and then see about overclocking in the future if need be as initally there is little to no difference. So in conclusion, FX-6300 + R9 270 and then put spare towards another 4Gb of RAM in future
Hope this helped!