Owning your own home

It depends how much of a git you are prepared to be to the landlord and the new tenant.

If you don't leave the quickest your landlord will be able to get you out by force (the bailiffs) is a month or so.

Assuming it's a proper agreement and has been properly terminated (has it?) even the Accelerated Possession system is slow.

Just remember that by being a git, you will likely be costing your landlord money (court fees, lost income, advertising costs, etc.) As you appear to be moving into home ownership, I guess you would be worth pursuing through the small claims court for compensation of their expenses.