I was in a similar situation (though DS dad did provide for him), a lot to buy for with not much money is hard. What I learned was to prioritise my own child first, then whatever was left was split between other people, which meant getting creative and savvy.
The Works is brilliant for children’s gifts, they have loads of deals on books, games, craft sets. They look a decent present without breaking the bank.
They also do jigsaws and books which you could gift for adults, again some great deals.
In the past I have done a movie night hamper containing couple of cheap Christmas DVD’s from Poundland, crisps, sweets, popcorn and a couple of drinks. Cost approx £10. I was lucky enough to find large plastic popcorn buckets in a pound shop and filled them with the treats, but you could get cheap wicker baskets from charity shops, or somewhere like Card Factory.
You could mix it up by putting mini games (from Home Bargains) instead of DVD’s.
I would consider doing this for a family gift, or at least for couples & then separate ones for kids, to really reduce your costs.
I’ve also bought packs of mini wine/Prosecco, packs of hand creams and candles, split them and added small chocolate box (mini Lindor, etc) and made up gift packs for multiple people.
Someone else posted on here with a similar issue, so worth looking through the other threads for ideas.
Also keep a check on the bargain threads, I’ve picked up a lot of gifts already for a fraction of the price.
How old is your DD?