Don't need a mountain rating for anything in the UK, but if you want to learn a bit about technique and dangers, then you could do worse than an hour or two doing some of this.. All the lochs are generally by definition, in amongst the mountains, and it's a s##tload of fun
As mad_jock said, the "Mountain Rating" is not about flying in mountains, it is about operating from very steep (18.5% in Courchevel) one-way runways.