hi sketcho. as your friend has given the 2 months notice, and the tenant is refusing to leave, he would then need to apply to the courts for a possession order. This is likely to take another month or so, and in the meantime, the tenant are not required to leave at this point. What if your tenants refuse to leave even after the order is served? Under no circumstances are you, the landlord, allowed to remove the tenants. This can only be done by the court bailiff. You will have to apply again to the court. It may take two more weeks before the tenants are actually removed.
from your friends point of view, your local authority can advise him in his role as landlord (they should have something along the lines of a Private sector liaison officer), but i would also suggest to the tenant that she seeks assistance from the homeless dept asap.
i think ive waffled a bit, but hope it helps!