UK Landlord Forum / Life

I have a rolling contract with my Letting Agent which was originally signed in April 2010. I have tenants in my property , who's agreement runs yearly, from May to May. How do I cancel the rolling contract with the Agent without it affecting the tenants?
What do I do about the Agent's hold on the Deposit? One of the Agent's conditions is that he would normally return the Deposit to the Tenant at the end of the Tenancy Agreement.
I believe my Letting Agent Contract would expire at the end of each 12 months (in April) without me incurring penalties, but am I right?