You are now on a statutory periodic contract.
Your tenancy agreement is as legal as a new signed contract, only special terms in it are potentially able to be challenged. Notice periods above and beyond the statutory 2m for landlord, 1m for tenant for example. Otherwise the terms do hold.
Statutory Periodic Tenancies
These tenancies usually come about when the fixed terms of Assured and Assured Shorthold tenancies come to an end but the Tenant stays on ("holds over") with the Landlord's consent. The terms of the tenancy remain the same. In the case of a periodic tenancy following on from an Assured Shorthold Tenancy the Landlord and the Tenant both have the additional right to end the tenancy by giving the required amount of notice
I got all this from here
What are my responsibilities for repairs to the property?
The respective responsibilities of the Landlord and Tenant for repair and maintenance of the property should be specified in the agreement between them. If they are not the responsibilities will depend on a number of factors including the length of the tenancy and the date it commenced.
In general the Landlord will normally be responsible for:
ensuring that the property is fit for habitation at the beginning of the tenancy (if let furnished)
repairing the structure and exterior of the building
repairing and keeping in working order the water, electricity and gas (if fitted) supplies, and the sanitation (drains, basins, sinks, baths and WCs)
repairing and keeping in working order the room and water heating equipment
the common areas in multi-occupancy dwellings
You will normally be responsible for:
using the premises in a tenant-like manner, doing such small jobs as unblocking drains, cleaning chimneys, mending fuses, etc
repairing and damage which he or she has caused
keeping the premises clean
He failed to carry out his responsibilities under the original contract, so was in clear breach then. Do you have any written communications to back this up?
Go talk to the CAB, they will tell you who to talk to in the council to get the work done.
Don't panic, this is all doable, if all else fails you can withold rent in lieu of the building costs. But get a solicitor on board to help if you can.
Definitely ring the environmental people.