Many many guestimates Incoming. Also I haven't gone for the cheapest imaginary version of everything as I didn't think that's what this question implied. But I've also not been super generous everywhere either.
3 holidays a year - one long haul two smaller European city breaks type - £1500 per city break and £5k ? Long haul, so £8k minimum, I reckon more like £10k?
1 nice car bought outright - nothing majorly expensive around the 60k mark - so that's gonna last say 10 years, so £6k per year,
coffee out for both adults x5 a week - £40 PW, £2000 per year
lunch out for both adults x2 a week, £30 PW, £1500 per year
dinner out every Friday - whole family two adults two kids - £160 pw, £8000 per year
good Christmas every year - £3k per your statement
money for regular hair appointments for whole family: let's say 10 per year at £20 for the gents and 5 per year at £50 for the ladies, so £1000 or so? That is a guess, obviously highlights or whatever would add to it and I'm fairly sure there are cheaper men's places than that.
enough money for both kids to do sports and music out of school - £200 per month, so £2.5k per year
nicely decorated house - like £100 a year for paint? Depends if you pay a decorator
monthly shopping treats for all family members maybe £50 each - okay, £200, £2.5k per year
Food shop from M&S - £800 pcm ? So £10k per year
clothing to be mainly high street with the odd designer item thrown in for whole family. - say £2k per year?
What's that adding up to: £48.5k ? plus council tax (£250?), gas (£100), electric (£100?), petrol (£150?), boring crap (£200 - by that I mean MOTs, tyres, new washing machine, repairs etc), insurances (£100?), subscriptions (£200 - internet, phones, TV licence, car tax) etc.
What's that's gonna be, another £1100? Per month.
So that's about £5.2k a month take home net, plus whatever you need to save for big things like the boiler or a new roof or moving house, and retirement.
So not £100k by a single earner, but two lots of £50k probably just about doable if you don't have a mortgage. It would stress me out to spend that high a proportion of my income though. And if you wanted my estimates generous throughout I think you would easily be adding an extra £20k per year pre tax income before you put any extra savings in. And if it's a single earner you're gonna get got by the £100k personal allowance farce, so probably at least £125k
I think the other thing that's interesting is where you can make the biggest difference on costs: buy a 3-4 year old car and run it for 12 years and you'd halve the cost of that. And would it really give you any more joy to have a newer car?
Change dinner out every Friday to dinner out every other Friday and breakfast out on the other weekend (£60 instead) and that's £2k saved.
Or flip a long haul holiday to short haul every other year.
Etc etc etc. Obviously you would want to pick the things that bothered you least to "miss out on" but I reckon you could have 90% of the joy at 70% of the cost by picking the things that mattered most.