What you both need is accountability. A joint account that’s accessible online which is for bills only. Sit down and figure out your fixed outgoings (rent, council tax, gas, electric, insurance, loan, any other direct debits that are crucial). Move all direct debits to that account. Figure out what you’ll each put in each month to cover bills from your wage. Then figure out how much you need for food each month and who’s going to pay for it - you could also put this into the joint account but it means sticking to a budget and not just buying whatever takes your fancy.
You each then have a basic current account and a savings account. Personally I like to put all my excess money after bills into a savings account and then transfer what I need to my current account throughout the month - I don’t like taking money out of savings, so I’m more likely to think about whether I need to buy that. Agree to how much you will put into savings each month and hold each other accountable. If a big purchase needs to be made, you need to talk to each other first. I would suggest a joint savings account so you can see what he’s doing but I suspect you’ll end up saving far more than him so you might want to keep it separate.
The key to all this is to communicate about money which can be really difficult in the beginning. You both have to be onboard and you both have to let the other one know how you’re doing financially. No secrets, no surprises. I wouldn’t like to have entirely joint accounts, but you could try that if you think it will help. The important thing is that you both need to keep track of your incidental spending if you do that or you won’t have enough to cover bills.
My husband and I don’t have a joint account at the moment but each month we check in with each other about how much we have, how are savings are going, how much (if any) debt we have (usually we have none, but we’ve had to make a couple of big purchases lately).
I make most of the day to day purchases of things for the kids like clothes and toys, but if I need to buy something expensive I let him know. We had an hour long discussion about potentially buying a new laptop for his work a couple of weeks ago, then our boiler broke down and we had to replace it, so that’s on the back burner.
Shop around for everything. Use something like quidco. Google voucher codes before you order anything.