a room which provides sleeping and living/study space and occasionally a cooking area

a single, smaller room with all the facilities in the one room (a small two ring cooker, fridge, and a sink or basin would be typical equipment)

a teeny little apartment

A bedsit, also known as a bed-sitting room, is a form of rented accommodation consisting of a single room with a shared bathroom and lavatory; they are part of a legal category of dwellings referred to as Houses in multiple occupation. In some cases the room has a small formal kitchen area but it is common for the tenants to have no more than an electric kettle and single electric ring.