I'm in the same situation but here is what I've done.
I work 24 hours a week, my youngest is still in nursery until September so I get 30 hours and pay the rest. When it's the school holidays my eldest goes into holiday club, I take holiday or their dad takes holiday. Whatever childcare I pay for I submit to Universal Credit and they will pay back a percentage.
In September I'll increase my hours and work a bit over 30. I'll be using after school club twice a week so again I'll submit that to UC and they will give me some back.
I currently live in my mortgaged house but the plan is for my husband to buy me out and remortgage to raise the funds. This should give me a bit over 40K so my plan was to put 30K down on a shared ownership house and get a mortgage for the remaining amount I was short for for the share. However despite going through a mortgage broker I couldn't find anyone to lend me the 10K that I needed because I didn't earn enough and was paying childcare costs on top, they all came back saying they wouldn't lend anything. Luckily I have family to lend me it, otherwise I would be stuck because I can't increase my hours without using childcare. I would have ended up renting, my Universal Credit would be stopped because of the 40K from the house and I would be using that to live on, I would never be able to buy again.
I will be paying £300 rent and £100 for the money I've borrowed making my housing costs £400 total. I couldn't rent a one bedroom flat for that so shared ownership is cheaper and there is a bit more security but I do have to pay a service charge every month to the housing association and I'm still limited to what I can do with it so no major modifications. It's the middle ground between buying properly and renting.
The downsides are that I'm moving to a smaller house, the kids will be sharing a room indefinitely and I have to rely on UC getting my money right every month or I'm left short.
I've no idea what the future holds, I need to find a better paid job because minimum wage isn't enough to live on in the future but for now one step at a time.
I hope I'm doing the right thing, there is a lot of issues in our marriage and despite counselling it isn't going to get fixed quickly if at all so whilst I have the opportunity to buy somewhere in my area I need to do it.