Ahaha, this kid is pretty much in the same boat as my younger brother (around the same age). The blighter spent ~£200 on a terrible barebones system and then a bit more on a decent SSD (the only good part in the whole build). Now he has ~£150 left for the graphics card which isn't too bad. Unfortunately, he went the Intel route with not even the great G3258, but a terrible G3450. Worst part is, they already have a Q6600 PC downstairs (I donated my old one to my family), but they somehow killed the graphics card when they gave it to someone else (without my approval) to install a non-SSD hard drive (the person thought it too costly).
So all I'll ask is, do ya already have a PC and if so what is it? Cos you might be able to get away with a mere PSU and graphics card upgrade, which will be better value for money. Otherwise, go AMD, though I personally have no clue about AMD processors. Also look to snipe good deals, there was a great deal on a R9 285 the other day where it was less than £100 from the usual £150+ price point. My advice... have patience. Spend time researching the parts and checking prices before you commit.