I'd expect you are on a Short Assured Tenancy (or whatever the English equivalent is).

That means it runs for a minimum of 6 months but can be extended thereafter, either informally on a month-to-month basis till one party gives the other notice, or formally by way of a new Agreement.

There will be a clause that allows your landlord to give you notice to quit, and normally one that allows for rent increases too.

Find your copy of the lease and get down to CAB with it asap.