Please, I'm begging you, please call Habitat for Humanity. Don't make assumptions based on what you think you know about the program or have heard, just fucking call.
Worst case scenario: You spend an hour at the initial meeting and discover it won't work for you. The other scenario: You end up owning a brand new home (or one refurbished to brand new) at cost.
Because my es-wife picked up the phone, I now own my own home at $600/mo., 19-year mortgage. Took us right at a year to complete the program and have keys in hand.
Be glad to answer questions, but there are variations according to the local outfit's way of doing things.