If you are 43, loads of money unless you are planning to end it all by the time you are 63.
Now I may be talking bollocks and there are many more financially astute people on here than me, but if you had 1 million pounds, that’s £50k a year and in twenty years time the spending power will be like having only £25k which is nothing really.
To outstrip inflation you would need to invest in medium risk investments which fair enough you may win on but you could also loose, leaving you in your 60s with nothing.
It seems like a good idea but unless you are loaded, or have some serious assets you can liquidate if you need to it’s very risky and you will need to live like a monk.
Have you thought about just reducing your hours ? That way you can get a better work life balance but without the risk.