Studio Flat that isn't a Studio Flat

Tenancy Types and Management

I am trying to find tenants for a lady who lives in her house and rents out the top room. She calls this a studio but this is a bit ambiguous. It has an ensuite bathroom, but the tenant will share her kitchen with her and does not have a separate entrance to the studio room - having to come in the same front door and walk through the house and up the stairs to get to the studio room. As this is a resident landlord, does she have an AST or a Licence to Occupy? The tenant will have exclusive occupation of the studio room but shares kitchen facilities with the landlord who occupies the rest of the house.

Thanks
Lucinda Watts