Toms spec above looks very good for your budget.
I would however strongly advise that you consider upgrading to a Skyfire II. The price increase of £20 not only bumps the chassis size up to 17", but the upgrade from a 660M GTX to 670M GTX (click 660M/670M for links to performance benchmarks) will give you a SUBSTANTIAL performance improvement (20% in SC2, 35% in Diablo 3). The chassis size increase may seem like a burden, but from personal experience (see my laptops in my signature below), the difference between lugging a 15.6" and 17.3" around is negligable.
Regarding your CPU: The sandy and ivy bridge i5 dual cores are certainly potent, however games running on Blizzards proprietary engines (sc2 and D3 in particular) are extremely CPU intensive. I would recommend opting for a 3610QM as a minimum.