I would say that, whilst you are sharing a house, it would be reasonable to expect a contribution. However, as you will find out with divorce, 'reasonable', 'legal' and 'moral' are all 3 separate areas and what you or I might consider reasonable and the right thing to do, there will be no legal obligation for this to happen.
Sorry, I know this is not what you want to hear.
It rather seems she has no legal obligation to pay a share of the bills and given the acrimonious state of play very unlikely she'll contribute.
I'm going to have to make every penny count and stay in the house to maximise the time I've got available with the kids. My solicitor advised she starts several pegs ahead of me as the judge is likely to place two of the daughters with their mother although the eldest is free to choose who she lives with. My only hope seems to be a CAFCAS report leaning heavily in my favour.
My friend, as you have a solicitor, you are recommended to take his advice, which looks perfectly OK to me, but undoubtedly, the main issue for you will be housing.
Your solicitor is right, the Courts will put the children first, and often this will mean that the Courts will give priority to the needs of the custodial parent. On occasions this can lead to particulrly nasty results, I saw one the other week - but the circumstances were admittedly unusual. And at the end of the day you must have somewhere to live too.
So there is likely to be an issue as to wether she could afford to live in the FMH with the aid of such resources as she has or could acquire. These might include maintenance ( child and spousal ) tax credits, benefits, including JSA, Council tax benefit, child benefit, etc etc etc.
It may be that this will turn out not to be possible ; in that case there is no option but to rent. In that even she could claim housing benefit as well.
My usual advice in such circumstances, and I see no reason to depart from it, is not to go until you have to, be as nice as pie to all your family ( which may not be easy ) and as you say, enjoy time with your kids. You seem to be doing things in the right way, and the ideal solution is to make sure that the children have regular contact with both parents.
What a heartwarming last paragraph to your reply LMM - thank you, I will certainly endeavour to stay for as long as possible. The hardest part is maintaining my cool in the face of almost intolerable provocation.
She cannot afford to stay in the family home. However if I got custody and received Tax Credits/Child Allowance for all three kids I WOULD have enough income to stay. This would be coupled with the reduction in bills covering her, shall we say, addictions.
I have no objection to regular contact however my circumstances/spouse behaviour lead me to think a favourable CAFCAS could potentially mean the children living with me.
I hope you'll respond again as I'll undoubtedly return here as the process progresses - thanks again.