With regard to any savings etc take your half and then from his half half the costs for applying for divorce etc as that is a shared cost.
Make sure all the bills are paid to date from any joint assets and change your salary to pay into your own account if it isn't already.
Go through all the bills and reduce as much as possible across the board - you will struggle to afford the house by yourself and best to reduce costs and cut back now than even in 3 months.
Get a valuation on the house (in fact get three), Get a solicitor sorted to sell the house asap and get it on the market.
Start looking for something more sustainable for you and daughter to live in - am assuming he is not taking on that responsibility - mainly as they just dont!!
I would sort a solicitor for the financial settlement - you will have to put money down for this unless you are entitled to Legal Aid which is v unlikely
Do let family know whats going on and ask for their support for daughter in particualr - even his family.
I would make sure she has all her uniform, PE Kit shoes and trainers etc from joint funds too before he goes, I personally would make a point of he needs to come and do that with you both so he can see the cost of these things and you can prime him for splitting the costs in future on top of CMS - too many Dads assume its all included without realising it could be a couple of hundred quid for secondary school.
Expect the worst of him - then you wont be disappointed. Be as proactive as possible as you will catch him on the back foot making it hopefully easier all round. Let him explain to DD as well.
Good Luck