The nearest sites are Chesterfield Imperial Airsoft, which I've not been to yet.
Tac-House: Spartan in Chesterfield, which is run by the guys who ran The Stan. Though in my opinion isn't a 10th as good as The Stan was, but it's CQB and it's close. It's run by people who know what they're doing, and since I went on the opening day, I imagine it's improved a lot.
Blackdagger Airsoft in Dronfield, which I've also not been to.
Brit-Tac Woodland in Barnsley, which is excellent.
Skirmish Airsoft near Worksop/Mansfield, s'about an hour to the South and it's my regular site, they also have their own on site shop, do a price match guarantee and will let you buy a gun pre-UKARA in proper colours, so long as you sign up to their membership scheme and don't take it home until you've been 3 times.
Though as above, you'd be better off playing at least once before deciding to put money into it, 'cos it's one hell of an expensive hobby if you catch the bug for it and buying a gun for over £100 before you've even played, only to find out you don't enjoy it, would be a horrible shame for your wallet.