Office use of old derelict barn

[Warwickwater2]

I live in a converted farm building (one of about 10) that originally formed a working farm in Kent, in an AONB. There is one building remaining unconverted, a wooden framed, steel sheeted 'shed' maybe 1000 sq feet total. Am I correct in thinking this could be used as a B1 office without any further permissions? The building is however derelict to the point of being unsafe - assuming this was a short term thing, how far would one need to go on 'repairs' before is was a new building requiring PP? Could I for example reverse a couple of converted shipping containers in through the doors and use them inside as is?

 

[Nakajo]

I would seek professional advice. You can do a lot, but it's very important that you do things in the right order, so only seeking the change of use after certain modifications have been made.