@purplepentagram I think that's the trap of benefits.
When children are included, especially if they qualify for any extra help, it can be quite generous, easily upwards of £1500pm after rent is paid.
Eg, My ds receives just shy of £3500 per month once rent is paid, but that reduces by 1 dc next year, and I'm always encouraging them to look to the future, and try to pick up more hours/ do some free courses whilst they can to improve their chances later on.
Obviously, though, unless the adults can/ are able to improve their employment prospects then it's a big shock once the children become adults and are no longer part of your claim as the amount for an adult is, by comparison, ridiculously low.
We had many years where our income didn't stretch far enough to pay for even the essentials, so I can sympathise with your current problem.
For Christmas, we focused on being together, and doing things that didn't cost much, eg, movie night at home with hot chocolate and marshmallows. I'd buy some Candy Canes from the pound shop (12 for £1) and use some to decorate the tree (cheaper than chocolate), and the dc would have 1 each in their hot chocolate.
We used to play cards and other games like pictionary, and we'd wrap up warm and go for a walk with the dog, then have a warm homemade Mince pie or jam tart once back.
I used to buy stuff over the year that they needed, eg, socks, gloves, knickers, a new PJ set and would wrap them all up individually as, especially when young, the fun is in the unwrapping.
They were allowed to open their PJs on Christmas Eve so they could wear them for Christmas Day, and we would end the evening reading the classic poem/story "The Night Before Christmas ".
Even though, things are easier for us now, we still keep to a lot of these traditions that we built up over the year.
Their favourite one is the once a year special hot chocolate that I make for watching our Christmas film (Love, Actually). For each mug, I melt a bar each of (cheap) dark and milk chocolate, I then add half a pot of cream and a handful of marshmallows, some Christmas spices, and melt it all together. Typically, even now, it costs less than a pound to make per mug🍫
Sorry it all feels so hard. It sucks.