[FionaVB]

To CassieG, I am still in Vietnam, still teaching at the same school four years after arriving. Re-reading this thread, I still believe that an on-line TEFL course is fine if you want to study while you are still working at another job. There are CELTA and other courses available over here too, if you are prepared to put all your eggs in one basket and come only with the hope of getting a job afterwards. Although, that is not difficult. There are plenty of good respectable schools here, and there are always teachers coming and going. One thing about Vietnam, though, is that they are now cracking down on work permits. In order to get a work permit, it is HUGELY useful to have a degree - of any kind. (It was possible to obtain a work permit without one in the past, but I believe that is more difficult now.) And then you need to make sure that all your paperwork is in order. USA paperwork in particular seems a real pain to get notarised etc.
Back to your situation, lack of experience is not necessarily a barrier (depending on the school), and I believe age isn't either. I know of several teachers in their 60's, and I'm pretty sure one is in his 70's already too.
Good luck with everything!