Can't answer for that poster, but personally I allocate myself about 125-150 per week to live off and find it easy.
Food shop in Aldi - £30
Train to work twice a week - £20
Social spending including a meal out and weekend stuff - £50-60
Maybe a new item of clothing/beauty products or a treat - £20-30
I don't have a car (live in London) WFH 3 days a week, don't have kids. Take home about £2750 after tax, outgoings (mortgage, bills, council tax, pet insurance, phone bill etc) are about £1200, I save £300, put £500 in a Monzo for all spends out of which I work to the weekly amount above. That leaves £750 in my current account which I pay some off my credit card from (currently about £2300 on there) or put towards bigger expenses like foreign holidays, home improvements, service charge for my flat, or put into savings.
I got a mortgage as a single person earning £45k for a 200k flat with a 10% deposit. I didn't have any family help. I bought my flat last year but prices have already risen enough that I don't think I'd be able to afford it now. It can be tight sometimes but I'm absolutely not in poverty!
If I had a child as a single parent, things would be much more difficult, but if I had a child with a similarly earning partner I think we'd manage fine.