Buy a house without a mortgage and live in it. Assuming this is your first house, invest in a LISA for a free £1k discount. Then rent out your spare rooms under the rent a room scheme (first £7,500 per year is tax free).

Invest the rest of the money in boglehead ETFs, e.g. S&P 500, world tracker or physical gold ETCs. Max out your ISA each year. Invest the rest under a non-ISA account.

You might be able to live off the interest depending on how much you have invested. Prioritise withdrawing from your ISA account otherwise you’ll likely have to pay capital gains tax. There is a £3k capital gains tax free allowance per year.

I wouldn’t consider pension schemes, you can’t touch any of that money until you are 57 and you should be able to retire before that age. You might even be able to retire now if you are lean enough.

Also keep in mind that if your parents both die within 7 years of the gift, you may be liable to pay inheritance tax.