A person is homeless if he has no accommodation available for his occupation, in the United Kingdom or elsewhere, which he—
is entitled to occupy by virtue of an interest in it or by virtue of an order of a court,
has an express or implied licence to occupy, or
occupies as a residence by virtue of any enactment or rule of law giving him the right to remain in occupation or restricting the right of another person to recover possession.
A person is also homeless if he has accommodation but—
he cannot secure entry to it, or
it consists of a moveable structure, vehicle or vessel designed or adapted for human habitation and there is no place where he is entitled or permitted both to place it and to reside in it.
A person shall not be treated as having accommodation unless it is accommodation which it would be reasonable for him to continue to occupy.
A person is threatened with homelessness if it is likely that he will become homeless within 56 days.
A person is also threatened with homelessness if—
a valid notice has been given to the person under section 21 of the Housing Act 1988 (orders for possession on expiry or termination of assured shorthold tenancy) in respect of the only accommodation the person has that is available for the person's occupation, and
that notice will expire within 56 days.