ok...as a singleparent who for a while after a nervous breakdown caused by ex and having to leave work i can tell u what you can claim....after baby is born, you can claim, local housing allowance two bedroom rate for your area...google your area, council tax full benefit, income support £67.50 weekly, child tax credit £108.29 when baby born, child benefit £20.30 before birth £33.70 after birth and child maintenance. You can also claim the healthy start vouchers £9.60 which you can buy milk and vegmwith at asda/tesco etc. Total equals £219.09 per week and full council tax benefit and keep maintenance. You can claim this irregardless of living at home, only thing you cannot claim is local housing allowance.
here is where it tells you what you can claim:
www.entitledto.org.uk
You can claim income support until last child is 5, then you have to work at least 16 hours...if you work before that you will gain working tax credits and get 70% towards childcare through tax credits.
Child maintenance does not affect at all any benefits now...work out how much he should contribute here.
https://www2.dwp.gov.uk/csa/v2/en/calculate-maintenance.asp
First you need to go to jobcentre and claim income support then ring child benefit and around for second child when he/she arrives and google healthy start for pack. Then when baby is born, register birth and then inform taxcredit and child ben, as a single parent taxcredits and income support will be done very quick.
If you need a deposit for a house then ask council andjob cente as they have schemes where they will pay or lend the deposit to rent, housing allowance again goes through quick as is linked to inome support.
p.s i usedto work for the jobcentre and do the benefit calculations lol!
goodluck hun