Can I "cheat" a little?
I am in the major city situation, say I have a lot of spare food,
, food is wealth don't ya know. I'd fill up everything I could with water, and hideout for a little over a month. Hopefully most people have died or dispursed, I'd try to make it to one of the islands out on lake misoka after that but I would require more people. One does not survive alone. It would depend on what exactly happened though, odds are your are going to need to make an army or join one.. Not the typical armies we see now but if things went to hell warlords would become kings again, be one or bow to one.