From October 2018 all properties, all properties occupied by five or more persons (who are not members of the same household) are likely to require a licence from the local authority.
There are three tests defined in Section 254 of the Housing Act 2004, standard, the self-contained flat and converted building test. If a property does not meet any parts of these tests, then a mandatory licence is not required.
As these tests can be very confusing, we would advise speaking with your local authority and obtain written confirmation that your property is exempt from licencing.