Were to get a bike from?

don't know any bike shops in Newcastle area but a bike shop (not Halfords) is always the best way as you'll have quick and easy access to any after sales service required, not an easy thing with web based companies. Also you'll be able to 'try before you buy', essential to ensure the correct fit. Most of the big manufacturers compete to produce the best mountain bike in this price range resulting in some great bikes, try Specialized, Trek, Giant, Scott.