There are quite a few programs that would help you to purchase a property with as low as 3.5% (FHA) and 3% DownPayment (My Community). If it is credit issues, there are several of non profit agencies that could help you to fix your credit, if there are items that can be fixed.
If it's because you don't qualify for a mortgage now, you better make sure you will qualify at the end of the lease term or you may lose your upfront "option" money.
If you think a rent to own agreement simply means you can buy the house later on, and use all the rent you've paid towatds the purchase, you are incorrect.
If you don't have an upfront deposit available, you may be asked to pay an amount of rent OVER and above the normal rent. Only that part of the rent, the overage, would be used towards the purchase.....or...you would forfeit that if you don't buy the house.
Make VERY sure you understand all the pitfalls involved in this kind of agreement.
Make sure the house has to appraise out.....make sure the seller isn't close to foreclosure or upside down on the mortgage..........there is a lot to consider.
If low credit is a probolem for you now - why not work on that first and then look into buying a home.