At age 39, I wouldn't waste time or money on IUI. In fact, I think the 20% success rate for IVF sounds very high. Is that a rate for pregnancy or actual life birth? A lot of pregnancies in that age range tend to end in miscarraige, but if they have a heartbeat at some point, they are considered 'successes".
I don't think you'll find too many charitable options for funding your fertility treatment. Loans might be possible, but you'd be gambling in a high stakes way with money you don't actually have.
How important is a genetic connection to you? I'd its not too important, you might want to look into embryo adoption.