Now, I like “Harry Potter” the way it is, but Rowling doesn’t go too many places with the Trio and friends: London, Surrey, and the Scottish Highlands. Obviously, part of this is because of what she knows about each; she was born and lived in England, but moved to Scotland much later. But you just have to ask: with so much space to use, where else could Rowling have taken Harry?
Choice 1: Wales. It’s connected to England geographically, so the students could have fled there readily enough without worrying about how. Plus, like Scotland, some native Welshmen don’t particularly care for the English who subdued them centuries ago, including Voldemort. You say you want a revolution…
Choice 2: Ireland. Not Northern Ireland, which is part of England and still fought over, but the rest of it. It’s free of British power, and therefore the Ministry of Magic should have no reach there. And again, the Irish would love a good scrap with the English, right?
Or Portugal, if she writes what she knows? Or France? The problem is that any of those places wouldn’t work: the kids can’t get to them, and Rowling wrote about Britain and the British.