"...How do you prepare for something like that on a budget?
I have a dehydrator, but I think meat only lasts for about a year?
They have those pre-prepared 12 month ration packs, but they cost thousands. So no good there.
..."
In this country (Hungary), Poland and in the countries further east, Romania, The Ukraine, Russia etc. Not being able to get regular access to certain foodstuffs was not uncommon, people didn't starve but they had to provide for themselves. Here as in many of these countries it was not unknown for families to own a 'weekend house' not so much a dacha as you might have seen in Dr. Zhivago more an oversized shed with a small garden plot attached. People would grow additional crops for themselves there, tomatoes, peppers, onions, beans etc. The whole family would be involved and the weekends rest would be given over to working that small plot and processing, pickling and preserving the results. It was also not uncommon for an animal or animals (pigs, geese) to be owned in common by an extended family or small community. Some pensioners might live in the area where the weekend houses were and would water and feed as necessary through the week.
I know many older folks in these parts and most attribute the ownership of these small weekend gardens to be one thing which kept real hardship at bay during the changes in the late eighties early nineties.
Property and land is expensive in the UK so a weekend house is probably not on the cards for most, but if you can take anything from the experiences here it is that trying to 'get by' on your own will be very difficult if not impossible.
Additionally almost all these folks know how to turn a bag of seeds into a future harvest, they have been doing it since they were kids, many of them can butcher a pig, duck or goose with no waste. These are the things you should learn, if you have never grown anything in your life start now, if you have no land use a windowsill or a garage roof, or find a pensioner with an untidy garden and offer to grow some spuds and such for you both, grow something, now, this year, get some experience.