Roz,

I recently read that there were going to be some changes introduced regarding planning permission.

I'm not sure if they're active yet but I recall that they would allow residents to undertake certain work without planning permission. I believe the changes included building a first floor extension up to a certain size and also extending the roof line a small amount.

However, I agree with BD. I think you should contact the planning department before the work becomes too advanced and establish whether it requires planning permission.

Depending on how advanced it is, if they haven't got permission and it requires them to to so, they might well go for retrospective.

Best of luck.