World and Celtique? Presumably you're referring to Salsa Celtica, half of whom come from Scotland (and who are a very exciting live act). But other headliners include Eliza Carthy, Spiers and Boden, Luke Daniels, John Renbourn and Robin Williamson, Lisa Knapp, Climax and Woodpecker ceilidh bands...the list goes on. I don't see where you're getting a world/celtic emphasis at all.

Camping may be a bit distant, but there's also cheap accommodation available at Jesus College. You get breakfast in the college dining hall and everything. Great music, and you get to play at being Harry Potter all weekend. What could be better?