Xscape Milton Keynes is good for practice before going to a ski resort in the Alps or any resort around the world, although having said that, it is in my mind only really suitable for beginners. For intermediates to advanced level skiers, it can be a waste of time as you have all the beginners in your way and its hard to get quality skiing done as a result.
It's the closest to snow that we have in England
You're not in the mountains
It may be an indoor slope, but you should go in there adequately dressed with gloves and waterproof clothing