If you don't need the 1tb WD black it will cost £410, the i3-3xxx series provides some good gaming power and the 7870 once you oc it will play all games at high, 1080p
Honestly, if it were me, if you are going to go FX 6300, might as well go for the FX 8120. I picked one up at Microcenter for 140. If you start overclocking that 6300 I bet it would whip the i3. Note, i3 can't overclock. From what I'm hearing, down the line, intel will leave socket 1155 behind. Vs you might possibly have an upgrade path later to steamroller and excavator if AMD brings them out.
the performance increase when oc'd in the fx range is 10-20%. This still doesn't make up for its dire core performance. The FX has a small advantage in applications but the i3 b*tch-slaps it in gaming.