Enforcement Notices and houseboats - Public forum - Planning Advisory Service (PAS)

I am looking at the possibilty of serving an Enforcement Notice in respect of a houseboat, used as permenant living accomodation and permenantly sited on the bank of a tidal river. I would be grateful for any advice from officers who have served Notices in relation to houseboats, in particular concerning: - how to identify the correct planning unit on the Notice - how to correctly word the breach of planning control on the Notice. Any advice would be much appreciated.