There are two categories for HMOs; the licensed HMO and the unlicensed HMO, well start with the unlicensed.
These would typically be an ordinary two-storey house let to 4 or 5 individuals on one tenancy such as friends, co-workers or students.
Such properties are typically outside the scope of HMO licensing, however it is important to check with your local council as each applies the supposedly standardised legislation differently.
Lending options are more limited than for a single let tenancy but there are a few lenders who will consider this type of arrangement.