The CPU is decent enough until DDR4 motherboards and CPUs come around in my opinion. You've not mentioned your memory or PSU but they're probably okay for the time being. So yeah, a video card. For £200+ I'd usually recommend a 7950 with good cooling however there don't seem to be any good deals with those at the moment (late November/early December is best for these deals).
Right now based upon current prices I'd get either of these 7870s:
You must login or register to view this content. or
You must login or register to view this content..