before you go handing over all your cash to lawyers, please consider my advice about getting an electrical inspection carried out - it will carry far more weight in court than any fancy lawyer in terms of showing that you're taking your responsibilities seriously as a co-operative.
This is a legal requirement for the managers of HMO, and as you're asserting that the building should be treated as being managed by a co-operative management body, then this body is legally responsible for ensuring that proper electrical and gas safety tests are carried out regularly on the building.
one last time - please get an electrician in as soon as possible or you will definitely be in breach of your legal responsibilities on that score*, which carries a maximum £5000 fine and 6 months in jail - maybe that will serve to focus your minds on the priorities here - no lawyer I know of can carry out a periodic inspection, so you will be walking into court guilty of not meeting this obligation if you don't get a spark in asap to sort this out for you regardless of how much you've given a lawyer to tell you what I've just told you for free.
Can't help feeling that I'm wasting my time on this thread though - fwiw, my NAPIT registration number is 13801, and I also run an energy & fire safety consultancy with 2 university professors that as part of it's remit covers 'Fire and Explosion Investigation, Fire and Safety Law, Fire and Explosion Mitigation' - these guys trained most of the HSE fire safety specialists for several decades. This is professional advise you are being given, please take it as such despite me not charging you for it.
*assuming the council are right about there being no up to date periodic inspection report in place.