PC Specs

700W PSU is overkill.
Read the Falcon Guide (search in Google images), its guidelines are very useful.

graphics card could be better

The graphics card is way underpowered. You won't get good framerates in most games or only at very low settings. Atm my preference would be at least a NVIDIA 660 or whichever AMD card is as fast. Everything else is just too slow, especially since you are pairing it with a pretty fast CPU.

If it just says 700w PSU, then it's most likely a generic PSU worth avoiding. It seems clear you're using some pre built site to config your PC. Look for a PSU from corsair/antec/seasonic/xfx, a 550-650w would be more than enough for that build. GPU is on the weak site, try to step it up to a 7770 or 7850 if possible.

For £600!? Aw hell no. Both the GPU and CPU are underpowered (don't buy non-K variant procs) and you could do better than that for that price. Here ya go;
£659 for this beast

Intel i5-2500K (3.10GHZ)
16GB DDR3, 1333MHZ Fast Access Branded RAM
1TB SATA III Hard Drive 7200RPM, excellent performance
DVDRW +/- DL high quality DVD re-writeable drive, dual layer support, fast and reliable
ASUS GTX560 TI Direct X11 1GB DDR5 Graphics
Windows 7 Home Premium 64 bit
Wireless Keyboard & Mouse provided! No cable clutter on your desk!
ANTEC (600) Six Hundred Gaming Case Case Branded 750W PSU
High Performance Asus P8H77-M Motherboard (4 Dimm Slots (Max 32gb) - HDMi/DVi, 2x USB 2.0, 2x USB 3.0 H77 Chipset
8 Channel HD Audio Sound
*WiFi - Wireless Internet Ready 802.11 b/g/n

Play around with pcpartpicker.com, remember to choose your country at the top. I've built a better one (well, AMD based but overall slightly better performance in games) for around £400, excluding OS, so make that £480 ish.

£600 is too much for these specs

Do not buy Pre Builds!!!, It's better to build your own, you can get more for your money ;)

Buy a bare bones and then fill in the gaps.. Novatech got some good barebones bundles on the go atm