UK Landlord Forum / Life

We have an issue where we have had tenant in our property for 14 months. He has been late with payments and now we have given him a months notice as he kept saying he was leaving anyway. He disputed his amount of deposit due back to him.  Where do we stand as it all seems to be on his side , do you have any leaverage.  I don't want to pay him more that what he is due just to get rid of him. Help