To reply to OPs original question (I think), I would say it’s a good idea to stock up on a couple of weeks worth of cheap non-perishables regardless, unless space is at a premium in your house. If you get an unexpected bill, that way you’ll still make it to payday.
If people start panic buying, then at least this boosts spending and the UK retailers, and presumably the economy also will benefit.
When the country I live in was hit by a huge natural disaster, even though in reality the supply chain in my area was fine, for a week people were panic buying things like instant noodles and toilet paper etc.
I didn’t really think about this as a possibility so I rocked up to the supermarket as usual to find many shelves empty. I got by, but I was single with no dependents.
Things calmed down in a couple of weeks. This country produces a lot of its own food though.
We have had higher taxes since, to allow for restructuring. If you can’t afford an extra tin of beans each week, well, you can’t afford higher taxes either.
As a side note, in order to eat pasta, noodles, etc. you need to be able to boil a kettle. If you live in a block of flats and are dependent on electricity for lifts, operation of water pumps to your WC etc then power cuts will be a huge issue for you.
Buy biscuits. Lots of biscuits. Try not to eat them before you need them in an emergency. You can always use biscuits.