I had to show my dh the finances of me on mat leave and going back part time to show we could afford it comfortably and still put money into savings. I had to do this hypothetically for a 2nd child as well to show that we would be ok.
Work out your basic monthly outgoings, so household bills, budget for food (£100 week?, petrol and car costs, and then things you generally need so x amount for clothes, hair cuts ect.
Then figure out how much is left that you could save. I also budget for us to each have ad hoc spending money.
With these figures you can work out how much you need to save to have 12 months off work depending on your works mat leave policy. So how much you get per month.
I did it by week as my mat leave pay was 1-6 weeks, 6-12 weeks, 12 -39 weeks. so what my weeks wage was with the smp if eligible for those weeks.
I have to save about £5k for us to be comfortable and me to have 12 months off.
Don't forget you will have about a month of holiday to take, including bank holidays, and you get £80 a month from the government.
Childcare if you want nursery you will be paying between £50-£80 on average for a day depending on where you live
Depending on what you want to buy baby you will need about £1000-£2000 to buy all the essentials. You can buy things much cheaper 2nd hand but that will be personal preference. Only thing we bought new was the pram and car seat, I probably spent about £500 In total by being savvy.
What I will say is that you do find a way to manage and you adjust your lifestyle to pay for baby essentials.
If you can present a well thought out plan with baseline figures etc and your dh still says no I would wonder if he does want kids.
My dh said he didn't want another but with my plan and reasoning we are going to try again in a few months.