Few of us today really know what we eat. This is because most of the food we eat is bought on impulse - or near impulse - weekly or even daily as we need it. Even adding together what you buy now won't necessarily tell you what you may decide to eat home grown. Peaches are expensive - but we feed the surplus to our geese. That means we don't buy goose food - or any number of 'cheaper' alternatives to peaches and cream for dessert.
If you want a 'self sufficient ' garden you need to be able to look at your garden. Work out different ways of using space. Backyard Self-Sufficiency is the neccessary book to get it started.
Buy Backyard Self-Sufficiency by Jackie French from Australia's Online Independent Bookstore, BooksDirect.