Survival Scenarios are something that it does well to consider, in case of some kind of Human Disaster, and being prepared never did any harm.
Wherever you live, your goal has to be to make an excursion or two to suss out the prospective resources in your area. And if you live in the heart of town, suss out the quickest and safest way to get out into the countryside, bearing in mind, the roads will be jam-packed and immovable, so main highways are to be avoided.
In worst-case scenarios, a small back-pack with a torch, a good knife, a light poncho and a water bottle should be taken along. There's a huge number of edible plants, tubers, mushrooms berries, and so forth available but they can be very dangerous unless you take the trouble to bone up about them.
I saw a BBC programme about Neolithic Foraging and these two guys were on a rocky coastline with lots of pools and they dug up tubers and collected seafood in the pools and they lived of the land, as it were, and ate very well for two weeks, as an experiment. There was an amazing collection of stuff I'd never dreamt of looking for.