As long as it is water proof, gas-filled, one-piece, with multi-coated optics and has a good warranty on it you'll find something perfectly good between £200 and 300. If you buy it from a USA online-retailer you'll pay approx 30% less than from a UK based retailer -, even after taking into consideration the P&P and Duty. It will also arrive within 3-4 days - something few UK retailers will manage. Yes, we do live in 'rip-off Britain'.
And don't be seduced by the marketing men who want to make you think that you can't be successful and aren't a serious stalker unless you spent £1,500 on a scope!
A funny example: I took a friend out last Saturday for a Stalk and let him shoot with my rifle, a cheap-as-chips Howa .243W and a budged Sightron S11 6x42 fixed scope. (His own rifle is an expensive German one -Beautiful wood, engravings, exotic heavy caliber, you name it- , his scope is a variable Austrian something starting with S for £1,500+) - He dropped a roe doe and later, over a pint, he said: Amazing, the bullet hit exactly where I put the cross hairs!!'. Yes, amazing.