So your DH goes on about needing to cut back but also appears to have no idea about how much he is spending?
You need to discuss a budget now, or else the plan is doomed to fail.
I would separate 'spending money' from bills and savings for annual expenses.
Get all your money paid into one account and transfer an amount to cover regular bills to another account, with the bills coming out of that account, and it not touched for other purposes. Aim to keep just enough to pay bills in this account, plus a small buffer in case anything goes up.
On payday, put money away for annual and irregular expenses and do not regard this money as available for spending on other things, only for things like insurances, holidays, Christmas, broken cars, pets and washing machines and the like. This is likely to need hundreds of pounds a month and is where a lot of people come unstuck, because they don't save the money and then fritter it away.
Then you need money for food shopping, travel to work etc and child expenses, so maybe either put these on a credit card that is paid off every month, or send a standing order to a separate account if you prefer.
Only after all the above can you consider personal spends for adults, splitting what is left 50/50. Maybe go through the above exercise on paper and try and work out what your DH has been spending up to now and how it compares with what will be available going forwards. Get him to think about how he will stick to an affordable amount.
Also worth checking that all your bills are as low as possible and going through the MSE money make over.