I think there's a rule about 30 years - if it hasn't been a habitation in the past 30 years maybe you'd need change of use planning permission? I say so because there's a house in our dale which is getting close to that and everyone keeps saying 'if R doesn't do something about that house soon, people won't be allowed to live in it again'.
Hopefully the barn you're looking at is inside that time frame?
Is there someone old in the village who would know? It
is fascinating finding out how things used to be, what was done where

Good luck
