As of 20 March 2019 the new legislation Homes (Fitness for Human Habitation) Act 2018 is coming into force. This implicates that all landlords or agents in England must ensure their rental properties are fit for human habitation at the beginning and throughout the tenancy.
If they are not, the new act gives tenants powers to take landlords to court for breach of contract, force them to carry out improvement works and claim compensation. Landlords can potentially be sued for damages for the entire length of the contract.
Most landlords should have nothing to worry about in respect of the new act, only landlords of properties suffering serious disrepair issues should be affected, and these should be resolved irrespective of new legislation.