When I did my tour of Scotland I didn't bother with all that work permit and visa stuff, I was able to borrow a sound system and a guitar from Gordon Menzies of Gaberlunzie.
When I landed in Aye, or was it Glasgow? the officer said if you work for money without a permit you could end up as a guest of her majesties government.

If you land here without any signs of going to work you shouldn't have any trouble. No one is going to follow you around. If you do a house concert around here I can loan you two regular guitars, a 12 string guitar and a 5 string banjo.