We were doing this, thankfully, for years, as our city was badly hit by Storm Desmond in 2015 when the city was without electricity for around 3/4 days and suffered haphazard interrupted power for another 3/4 days afterwards. Shops were closed, no trains/buses, no petrol stations, and both landline phone and mobile phone networks were "down" for the first couple of days.
Luckily we had an old battery radio so we could listen to our wonderful local radio who managed to carry on broadcasting by diesel generators, lots of loose wires around their studio and torches/candles, and they managed to keep everyone updated.
We've always had a bit of "stock", i.e. candles, torches, bottled water, and lots of tins/packet foods, so we managed fine, cooking on a camp stove.
We also had cash, but it really was useless because the shops were closed anyway, so there was nothing to buy.
We were very glad to have reserves, and have built them up even more ever since - we're not in "tin hat" territory, but we could be self sufficient for a couple of weeks if whatever happens, whether another bad weather incident, or cyber attack, or whatever really.
It's actually frightening seeing how literally everything closed down when there's not electric. Cash really won't help if the buses aren't running, the shops are closed, etc.