Is universal credit not supposed to solve this problem.
Universal credit has made it worse imo. If your assessment period ends near the date you get paid, and you get paid early, you're very likely to be entitled to nothing the following month. So they close your claim, without any warning.
Then, when you find out you haven't got the UC payment you were expecting, you have to start your claim all over again, provide all the evidence and wait 5 weeks (minimum) subsisting on just your wages and child benefit.
It's highly unlikely you'll be able to pay your rent in full. As soon as your rent is 2 months in arrears (which it will be: as UC pays in arrears, almost everyone relying on it is a month in arrears most of the time), your landlord is likely to issue a notice seeking possession. Homelessness beckons, and if you and your kids end up homeless because of rent arrears, the council won't help you because you'll be intentionally homeless.
And that, dear readers, is one of the reasons I moved out of homelessness prevention and into benefit advice.