You need your Solicitor to draw up a Separation Agreement, listing all your wants/terms and they send it to his Solicitor. Do not trust him to sell the house and give you money. You MUST do everything formally. It will cost about £1500.
Child Benefit is always paid to the Mother.
When you sell the house and split the proceeds, you are entitled to more cash than him because :
a) You are entitled to "economic recompense", as you gave up your career to care for the kids and he did not. This means you have been financially disadvantaged and you get compensated for this.
b) You are entitled to more cash, to account for his Pension. If he has a Pension that's bigger than yours, you get the cash equivalent.
eg....House sells for £400,000
His Pension = £150,000 as at the date of split
Your pension = £0
So, total assets = £550,000
Means you get £275,000 each.
Your whole £275,000 is in cash (from house sale proceeds)
He gets £125,000 cash
Plus £150,000 pension
This last thing was what enabled me to leave ExH. He had a big pension and I did not. Simply because I had worked Part time for years raising his kids.
Of course there may be other assets too. If your car is cheaper than his, take that in to account too.
Good luck!
ps) you really do need a shit hot Solicitor, they are worth their weight in gold. If you can't afford it, I'd suggest borrowing the money as you know it's only a matter of time before you get cash from the house sale.