buy flour and salt, make your own bread/tack.
hunt/trap rabbits, rats, deer, fox, geese, fowl.
salt the meat or cure it over a fire.
make jerky and pemmican.
collect wild edibles and berries
a hunting bow costs around 100-150 and is unregulated almost everywhere, here in australia i can walk into a shop and walk out same day no license required, and i am free to take any invasive species on crown land, europe must have similar rules, im sure in north america you can do whatever you want especially with the huge deer overpopulation. a decent 2nd hand bicycle should be 50-100, make sure the spokes are tight, no rust on the body or wheels and that it can support your weight + another 30kg
whatever you catch you skin, quarter and butcher quickly, wrap it, put in your backpack and cycle back home when you have enough meat. 1 deer can feed you for a month, and you should harvest 30-50kg from it, 2 rabbits will last you one day, a game bird will feed you for a week with a meat and vegetable stew. learn to cook food that stretches, like soups, thick broth stews, potato and beans and peas are your friends. cheap vegetables that keep you alive. milk should be cheaper if you get it from a farm directly. with experience things become easier to do. mora of sweden make good knifes that last a lifetime and are inexpensive. some people like to buy cheap disposable scalpels for a few dollars a pack of 10 and use those to skin and process meat. hunting with a bow requires patience, practice and getting within 15 meters of your prey animal without being detected, it is a rewarding skill which will not diminish with age and furnish you with various other skills, tracking, sighting, windage, camouflage.
now to the question of living, a cheap 2nd hand van can substitute for a sleeping space, bought and converted for around 10k, it provides mobility and privacy. being homeless is not the end of the world if you live above the frost line, you will need to build yourself a semi-permanent shelter away from other people, with the density of human population in the past 50 years most wilderness places have been abandoned, you would be surprised how much there is near you, check on google earth.
if you cannot make this transition to self-sufficient survival off the land, you will probably get poorer and poorer until your health suffers and you succumb to some malnutrition or preventable disease. with enough skills and patience any person on the planet can feed themselves well for a small amount of money. it requires you to be a lot more physically active, and without care accidents will eventually shorten or decrease your quality of life. Dick Proenneke spent over 30 years (from his 50s to his 80s) deep in alaskan territory in a log cabin he build by hand with minimal equipment. It can be done, safely, successfully. Harvesting free wild game within distance of you right now is a trivial task by comparison.