An interesting scenario. I can only offer suggestions relating to CELTA. Your experience of presentation will be useful, bt you don't mention if you have had any experience of training, unless this is implied. In my humble view, those who have spent some years in training environments with adults can progress to a teaching situation quite easily. Although they are different disciplines in many ways there are similarities. On the other hand I have seen far too presentations that were basically MS PowerPoint presentations and they were awful, lacking focus and nothing more than a reading exercise for the presenter - we used to call it "death by PowerPoint".

CELTA is recognised world-wide but is an entry level qualification for those intending to teach ESL to adults. It will not give you " qualified teacher status" but will provide a good grounding in methodology and organisation with observed classroom practice- both your own teaching and that of highly experienced teachers in this field. It's not a course for the faint-hearted as the 4 weeks are packed with lectures,assignments, lesson-planning, private research and intensive reading and of course classroom teaching. With the amount of lesson preparation involved you would be working until probably 11pm each evening and weekends. Having said that I would recommend this course. There is a pre-course task that will examine your motivation for teaching, your existing knowledge of grammatical structures, communication, and your sense of how you intend to develop as a teacher. Although I found the going tough I really did enjoy the course and had found a job within one month of qualifying, but I do have postgraduate qualifications and years of experience in teaching and training. Just ensure you choose a good provider for your course.