Hello, my name is Jim and I am a qualified lawyer happy to help you today.
By law, landlords must ensure the property is in good repair under S.11 of the Landlord and Tenant Act 1985.
If they do not, they face prosecution by the local council and can be fined. It would also be breach of contract on their part and you would be within your rights to terminate the tenancy agreement.
The Local Authority Environmental Health Officers have powers under the Housing Act 2004. They have a duty to ensure that properties in their area are in a habitable condition, and will serve improvement notices on landlords of properties which are assessed, under the new Housing Health and Safety Rating System as having ‘category 1 hazards’.
Similar powers are available to Local Authorities under the Environmental Protection Act 1990 if the property is considered a threat to public health.
I would therefore contact your local council (the housing department) in the first instance to report the matter and ask them if they can send someone out to do an inspection. You could terminate the agreement based on uninhabitable conditions but it would help if you had something in writing from the council before you do this.
If you do terminate and move out, assuming the landlord has your forwarding address they may try to sue you for breach of contract - you can defend the claim though (which is easy to do) and you can come back to this for guidance if it gets to that stage. Further if you want me to find the number for your local council to contact, can you confirm which area of the UK you live in and I will find the details for you.
I hope this helps - if you can please accept the answer and give me a 5 star rating (there should be a button at the top of your screen to do this), I can answer follow up Q&A's at no extra charge and Just Answer will credit me for helping you today.