What a pile of sexist shit @SunnyD44
How on earth is the OP’s husband going to look after his kids while working all hours? And how will the kids be better off without their primary carer, who has far more time to look after them.
OP - you need to get some help and and woman up, you are be scared of your husband, and to want to walk off without the dealing with the messiness of separation.
But if you do this you are abandoning your kids. This is not on. Separation is always messy, but your job is to get yourself and your kids the best deal.
In the kindest possible way - you need to get help and support to act like and adult and a parent and fight for what is best for them.
You are the primary carer and you have more time outside work than your husband. The court is not going to allow your husband to stay in the house and turf you into a bedsit. Don’t be stupid. Either you will sell the house and buy two cheaper places, or you and the kids will stay until they are 18, at which point it will be sold and split. You’d husband doesn’t need to ‘agree’ to this. The court will decide.
so
Pull all your joint financial info now, pensions, salaries, savings, mortgage. Go and see a solicitor. They will tell you how the money will be split.
your husband can ask for 3 nights a week, but given the age of your youngest, the history of care, and the difference in your working hours, the court is unlikely to agree it. What they will probably do is give you primary custody, with your husband paying maintenance with the proviso it can be reviewed as the kids get older. You will either stay in the house or sell and buy two new places.
in the unlikely event he did get 3 days a week it would probably not last 5 mins as the kids would be unhappy and he won’t be arsed.
Living with him full time is not in their best interests.
Get some help now - from a solicitor, your friends, family, women’s aid - to do what you need to do for your kids.
and no, of course you will not be able to wander in and out of each other’s houses once you are separated.