I would to leave my flat but my land lord reject and he asked me to pay him 2000 p just to end the contract?

i signed contract for 12 months and i lived in the flat for one months and i decided to leave it but the agent reject and ask me to pay 2000 p to leave they are already have the deposit so if i leave it and tell them that am gonna leave and i would not pay for the rest of the months what can they do if i am broke do they gonna sue me if thy will i will not have enough money to pay