I am a tenant in a housing association property that is riddled with vermin. what are my rights?

i moved in in may last year when signing the tenancy agreement it was already well known that they had an infestation yet they never bothered to telll me this. it is the housing associations fault as these flats were thrown up quickly and the pest control man said they never dug down far enough when they was built and so many coverings left unopen. he then left after few visits saying no more could be done. i fell behing with arrears of only around 300 replacing clothes linen eating out as theres no way you can store or prepare food here as they come out just after u do i have a 4 year old daughter who is terrified of mice and we have spent many evenings away from our home being on lil income paying out to eat out and travel late at night had its effect on what was left to spare coming up to the summer months was just making my arrears up as we can store food at this time of year and they now have decided to take me to court as i spent so long catching up. i feel like im living a nightmare just when i can relax because we are not over run with mice they put this on me what are my rights in court will they accept that i fell behind due to not being able to store or prepare food at home and replacing my childs clothes? whats my best course of action now? by the time i go to court next month all arrears will be paid up but then i will have the court costs!