At the end of your 12 month fixed term tenancy you became a periodic tenant, with each period running for the length of time between rent payment dates (presumably one month). During the periodic tenancy you can terminate the tenancy by giving the landlord 1 month's notice (in writing, I believe) to expire on a rent day - i.e. on the day your rent is next due.
Provided that is what you did & your rent was paid up to date, the landlord has no right to claim money for unpaid rent. Whether he can withhold any of the deposit for repairs etc. depends on the state you left the property in commpared with the state it was in when you moved in. Hopefully you had both check in & check out inventories done to provide the necessary evidence.