What an interesting post (which I could have written myself, except that we can't afford the gym, pool, or acting school)! It probably explains why Reform is doing so well in the Polls, as well-off (but not wealthy) families in higher-paid jobs are struggling to maintain a comfortable living.
OP - there is a big gap in your numbers. A PP estimated that your disposable income is £72k (£6k pcm) but you itemised spend of £21k. I'll estimate £5k for the holiday, & cars are a money pit - £1k - £2k depreciation p.a. before you start running costs, I suspect each car is costing £3k p.a.. Total Spend of £32k p.a - £40K p.a. MISSING.
If you seriously want to overhaul your finances find out where the majority of your money is going, and then decide whether you need to keep spending it.
To help you this is what we did:
We no longer shop in Waitrose (Aldi & Lidl do the job). In no way do I suggest that Waitrose isn't great value for money, but some of the Aldi & Lidl stuff is every bit as good, and there is a reason why Tesco & Sainsbury are price matching Aldi. (Personal tip - Aldi Porridge is better than Waitrose best).
UK Holidays. Especially Camping.
Energy saving - PV panels, & House Batteries are saving £300 pcm
Public Transport (selling the 2nd car - see above).
Walking/Cycling instead of the Gym.