Local Citizens Advice or your local council have a dept that deals with private landlords to establish your rights in this instance.Your landlord has an obligation to you as the tenant to make sure that that everything is as it should be and that necessary repairs and maintenance are carried out..otherwise he is in breach of the contract.If you were to leave the property under the 12 month assured shorthold tenancy agreement the agency will pursue you for the loss in rent until the house is let again...so be careful...in the same way if you were to withold rent payments for reason of poor state of repair..then the landlord can pursue you thro' the the courts to recover the amount of rent owed. Good luck.