How to regain possession of a property
You must get a possession order from the courts before the tenant can be made to leave. This applies even if the tenancy agreement has come to an end.
When a tenancy ends or is terminated by a Notice to Quit, the tenancy becomes a statutory one. This means that the tenant has a right to live in the property on the same terms as before until you obtain a court order.
You are not legally obliged to give notice to quit terminating a statutory tenancy, but may well be advised to do so since the tenant should be given reasonable notice of a landlord's intention to apply for a possession order against him. In order to regain possession you must prove one or more of the grounds set out in the Rent Act 1977. (For further information on the grounds for possession under the Rent Act 1977 see the ODPM publication 'Regulated Tenancies').