Funny you brought this up. I am working on getting a teaching degree. I am smart in the area that I will be teaching and years of field experience. However, with my poor grammer and spelling, should I not be teaching?
grammer = irony
I don't think it should discourage you. Having a teacher who can't spell has never been an inhibitory factor in my learning. 99% of the time we know what you're saying (even if someone pokes fun at you). Get someone to proofread your power-points or any assignments you put up, and be honest with the kids that spelling just isn't there for you. Language is a fascinating psychological field, there can be vast separation between intelligence and writing ability. Meaning, you can be smart but just not write. As long as you can teach, spelling shouldn't be something to stop you.