I mean, even if i can get the funds to take them to court, what leg do i have to stand on? There would be no evidence me and the Mrs got ill from this. And thats the same with my neighbour and her son. They can argue they were un-aware of the man holes, and got the thumbs up from building control that they are "satisfactory" once the mastic seal was put on. (again even though every where online states they have to be mechanically sealed).
Though, once they found our two manholes, they had to find the building plans and send them to the landlord and building regulators. Therefore surely they must have known about my neighbours manhole and should have investigated to see if it were sealed?
I'm not sure about taking them to court.
I would move out, not pay last months rent to fill your deposit pot for next place and you won't be out of pocket to them (or however long your deposit would pay for) and find another place.
The onus would be on them to chase you, just make sure you have as comprehensive documentation as possible to prove their breach of contract and communicate to them that due to breach of contract and severe issues you will be withholding rent in order to acquire the funds to move to a viable living space.
To me, that place is uninhabitable, so you have every right to get yourself out of there by whatever means necessary.
Sod taking them to court, not worth it... just get out.
Speak to a lawyer too - if you have contents insurance, it will often have legal cover for some advice.