I'm on benefits with one child and I get rent paid and 638.32 a month. Then child benefit is 24 a week.
That's to pay for all food, bills, travel, two people's clothes, toys, Christmas, birthdays and day in day out activities for her as I can't get much childcare as not been able to find work that fits.
If you have two children you might get about an extra 150 a month UC on top of that and half the child benefit on top. Nothing more with UC for three.
As you're saying your bills are 500 a month, you would be left with around £230 a month for everything else, although you would get a council tax discount for being low income and single adult household. You would currently get some help with winter bills, like the cost of living payments, but your bills would be higher as you'd be stuck indoors all the time. Or your travel expenses would go up from trying to find activities to do all day with your little one, and you'd have to constantly have a day's worth of meals prepped, for both of you, to keep you out of the house in the winter with heating costs.
Once my child starts school I'll be hoping to work and change things around. I'd love to be working and not parenting non stop and finding things to do on a tiny budget, with all the children's centres funding cut and minimal affordable groups/clubs for an under five year old.
You wouldn't get benefits anyway, as you'd have to sell your house or rent it out and you can't get benefits with over 16k in savings. They cap it once you've got 6k in savings anyway. The rent from you renting out your house may or may not be classes as income, not sure how they work that out with mortgage costs and if they award the rent part of UC if you've already got a property which you own.