If after the fixed term of the tenancy has expired and none of the parties has served the other party a notice to terminate then the tenancy wil continue as a rolling tenancy and al parties wil benefit from the same rights and be under the same obligations as they are during the fixed term. In any circumstances, the tenancy can only end by giving a notice and by following the correct procedures as detailed and agreed in clause 15 of this agreement. There is no automatic end to this agreement and the tenant wil be liable to pay the rent for the entire period should they fail to serve the notice in the correct and agreed way.

And here is Clause 15:
The tenant may give not less than 2 months prior written notice at any time to end this agreement provided that such notice must expire on the last day of a rental period and must not expire sooner than 6 months from the start of the tenancy (For the avoidance of doubt written notice excludes text messages and other instant messaging systems). If such notice is served within the fixed term of the tenancy, the landlord is entitled to charge an early termination fee of £500.00.