Normally, when someone applies for an extension of leave, the conditions of their current leave extend until the application is decided. In a case when someone applies outside the rules, though, I'm not sure if this applies. Certainly, he is not eligible to work, claim benefits, volunteer, get a library card, or anything that visitors don't normally do.
The only time we have seen a case like this on the forum, the FLR(M) took about eight months before it was refused, and then the husband's therapist had to step in and call the border agency in order to get discretionary leave granted for the wife.
I am very sympathetic to your situation, but I agree with the other posters. It will be far better for you in the long run to get a regular spousal visa. It will be much faster and save the hassle of your husband being out of status for all those months. Yes, it's expensive, but it's an investment in your future.