FWIW, I'm not forgetting biofuels. AIUI, there still is a de minimis and those who use SVO, WCO (straight vegetable oil, waste cooking oil [both filtered, of course!]) or make their own biodiesel don't need to pay tax on the fuel if they use less than 2,500 litres per annum. For that, this might end up as main or even the only route if my hunch is correct and commercial diesel supplies disappear from the public domain.
FWIW2, I used to run a 1995 Pajero 2.8 on 20% WCO and know people who ran their cars on 100% WCO with a pre-heater. They would start and shut down their cars on mineral diesel and switch to WCO once up to temperature. Goat Industries used to maintain a database of vehicles that could run on SVO (
https://www.vegetableoildiesel.co.uk/) but that no longer seems to work. However, there is still some good info on that site for anyone wanting info on making their own biofuels...