Owning a home is great, but please make certain your ready for all that it entails and you make a good choice. With one income, you have nothing to protect your family with if you were unable to work. With low credit scores you'll have a harder time getting a lender on board and they will charge a higher rate and fees then people with good credit will get.
My first suggestion for others in similar situations is to work on your credit. Depending on why it is low there may be some steps you can take to improve it. Get on a budget, save some money, pay bills on time and early, pay down revolving balances to 1/3 or below the limit. Dispute items on your credit report that are inaccurate.
Rent to own in a declining market generally favors the seller, not the buyer. If you pursue this option, make certain the agent you use is very knowledgeable and experienced in doing these transactions. You don't "own" the home until you've met the terms and obtained financing from a lender. The owner rents to you with a promise to sell and a premium on your rent. You may be better off paying low rent and saving the money for down payment on your own.
I don't mean to shoot down your dream, but hope to allow you to realize it without experiencing a nightmare. Best of luck however you proceed.
I wish you the best!