I am a teacher. I have been out of school now for 2 1/2 years and am still waiting for my own classroom. I have been subbing at a number of schools and yea was sick a lot. But since September I have been at the same school as a building sub, floating around covering meetings and teachers who had to go home sick (it is a HUGE school, so there was always something to do).
Now in the last three weeks, I have been covering for a maternity leave. It has been fantastic. Yes it is a lot of work. I have to plan, correct, copy things...but I would NOT change it for anything. I love what I do and there was really no other option for me. In addition to being in the same school all year, I have not been sick...since October! Crap...hope I didnt just jinx myself, I dont like saying that out loud...lol. In addition, I have NOT, I repeat NOT taken a day off all year! I am also taking classes for my masters at the same time. Most of my classes are online, so I find that much easier, so stress of drving to class or exposing myself to those teachers' germs.
Definitely try it out. Like Jane said, I am sure they need middle school math teachers, so hopefully you will get a job right away and that can be like a test. Or see if you can sub for a while first. Maybe you will be able to get a maternity leave and that would be your test. Dont give up that easily and DO make sure you tell someone about your CF...if you have a permanent job. I have yet to tell my administrators because my job is not permenent and I dont want to be judged. But I will tell the administrators if/when I get a permenent position, so that they can understand and not place CFers in my class.