@DarlingNikita is right - sit down together, and set out all the essential expenses - mortgage, bills, insurance, then, from what is left over, set an amount for the weekly food shop, an amount each as an allowance - he can spend his on wine or chorizo sausage rolls if he wants, and a bit to go in a savings pot towards holidays/family fun.
Dh and I did that when the dses were little, and we had somewhat lost control of the finances - we ended up with an overdraft at the end of each month, before he got paid. We worried about this for some time, before we finally got our act in gear and sorted it out. Initially, we used to keep a running total of expenditure, in the different catagories - we had sheets for our allowances, family fun and food, and if I bought myself a book, or nipped to Tesco to do a top up shop, I wrote it in the relevant column, and deducted it from the weekly total.
Yes, it was nerdy and finicky and a bit time consuming, but it worked, and we got control of our finances, and in time, it became second nature, so we don't need to religiously write everything down - although dh does have a spreadsheet on the computer that he updates regularly, and juggles money around the different budgets if an unexpected expense or bonus comes in.