i think we all are gonna be fine in a situation like that as long as we actually find food. it is perfectly fine to eat food that is a tiny bit over the edge. you would be surprised how resilient our guts can be!
the main problem would be finding water. because most people dont know which water you can actually drink.
salt water is pretty obvious. but your own urine and stagnant water also have to be avoided. flowing water is where its at and even then you might have problems.
your body can handle a little spoiled food but when you start drinking foul water your water input will end up being smaller than your output.
finding food should be a priority but finding water and making sure that people can find you have to be considered above all else.
There's several ways to clean water, NBC shelters need lots of water as well.
The thing is there won't be an event where we'll find food that would make us go on survival in the modern countries.
Nuclear, biological or chemical disasters/attacks will fuck up all food supplies and it will run out quickly, it will be hard to farm as well, lot's of animals would be dead and in case of a nuclear attack all electronics will be dead, so cars and lot's of other important things will not work. Water, soil and metal absorb radiation, chemical and biological problems will affect these as well.
Earthquakes and all will be "disaster" but we wouldn't need a real big survival kit because when you get pulled out, you go to the hospital in an unaffected area and live around there till shit is rebuilt.
So to summarize, "apocalyptic" scale events there wouldn't be much left out there.