Use Class? - self-contained student accommodation units, with no shared fac - Public forum - Planning Advisory Service (PAS)

Client has an existing detached house in use as C4 small HMO, (students as it happens). Client considering making a planning application to return existing house to C3, and build to the rear a very long single-storey building consisting of, say, 16 completely self-contained, self-catering units, (it’s a long garden) each having its own washing, lavatory & cooking facilities. There are no shared facilities at all, and all units have their own front door. My difficulty is, what is the Use Class? To me this is a terrace of very small houses, and therefore C3, and if they were arranged in a block instead of being strung out, they would be called “studio flats”. However, could they be said to be too small to be C3 dwellings, at say 16m2? Clearly, the intention is to let as mature student accommodation, but is that relevant, seeing as there are no shared facilities? Peter