Sourdough is indeed not only a solution to not having yeast to make bread, it is superior. I would like to offer some help to get started in this quickly. For me the learning curve was steep, but now I can easily make sourdough from scratch, with no mail order starter. Obviously if there comes a time when you can not mail order starter, such a skill could serve you well.
First, the idea that yeasts are floating around in the air, and form the foundation for fermenting sourdough is an old wives tale. Natural yeasts and probiotics occur on plants naturally as they grow, and the less modern synthetic farming or gardening done to your wheat, herbs/vegetables, or fruits the better for your fermentation, as well as your gut. Probiotics are very important for health. In an extreme case, if your intestinal flora dies, you die. The floating yeast being the way sourdough gets started myth is the reason you are told to put a cloth over the would-be starter. The idea is the keep dirt out, but let yeast in. I never do this. In fact, I make my starter in sealed canning jars. It works great.
I would like to put this in a larger context. Preparing for bad health is a bad idea. When you compromise, and store white rice, or other bulk death, you are skewing the calorie to life-giving-nutrition ratio strongly unfavorably against your family and yourself. I have heard many excuses for doing such madness as making half “white”/ whole wheat bread. If you take this to an extreme you could just store white sugar only for calories alone. As far as making bread, it is not easier to add white flour to the plan to somehow make things easier. It is ignorant and simply inaccurate. Also without going into depth consider the fact that so many people have “gluten intolerance”. This is because, again, people alter the natural ratio of wheat parts. Adding gluten is standard “industry” procedure. People get far too much gluten, and thus get messed up. Gluten is like glue. If you ignore this, and keep eating gluten white bread with all the other odd chemical additives, or such like, you are going to end up with digestive problems.
Sourdough  is the ancient, natural, biblical way to make bread. It would be best to grind your own grain eventually if you can not do this yet. Making sourdough bread  makes the bread more nutritious and bio-available, and gets rid of enzyme binding phytates. You basically cannot buy this bread in stores. Sourdough makes more nutrition available to your body.
The Food Encyclopedia  notes: “The culture is continually fed to increase its volume and leavening strength until there is enough starter (levain) to leaven a batch of dough with enough left over to perpetuate the culture.”
I’ll include some quotes from the Bible:
“And the people took their dough before it was leavened…” – Exodus 12:34
“… and bread which strengtheneth man’s heart.”Psalm 104:15
When man makes white flour out of the whole grain, they are throwing away precious gifts from God. They discard the germ and bran, which are loaded with nutrition. As the Bible says, bread strengthens man’s heart. However, not after man perverts the flour. In the modern industrial age when white flour started to be used on a wide scale, heart attacks increased rapidly. After studying the problem a few poor vitamin supplements were added back to white flour, by law. However this only helped a very little. We need the food ecology of God our creator.
“Another parable spake he unto them; The kingdom of heaven is like unto leaven, which a woman took, and hid in three measures of meal, till the whole was leavened.” – Matthew 13:33
“Give us day by day our daily bread.” – Luke 11:3
Regards, – Dash