OP, I earn just under 100k, which is about 5.5k per month. To earn this, I have to put my children into nursery full time, which costs me 2.5k per month. My mortgage is 1.5k per month. This leaves 1.5k per month. From this, I budget for the following:
300 food
250 council tax
150 gas, elec, phone, internet, insurances
200 savings to travel to see parents twice a year abroad, one week per trip spent in a really cheap hotel.
This leaves £600 per month. This pays for all other one off type costs such as annual car service / MOT, clothes for the children, house maintenance / repairs (eg we needed a new boiler this year, last year the gas pipes in our house developed a leak, the year before we had water damage etc).
I realise I am very fortunate. It's a comfortable life, but it's not a luxury life. To be able to earn so much I have to live in an expensive area, so have a high mortgage. Similarly I have to send my children to nursery full time. But these costs will reduce in a few years when nursery costs are replaced by wraparound care and holiday clubs.
Earning this amount of money gives me flexibility and choices. When I don't want to cook I can order a takeaway without worrying. When the mortgage is paid off I can think about reducing hours at work. Most of all, I don't have to worry about money, I can go to the supermarket and buy a food shop with extra treats without thinking about it.
I lived my childhood in poverty, counting our pennies before we went shopping, so I am really lucky to be in the position I'm in.