DELTA is generally considered a higher qualification after
CELTA, but CELTA is not strictly a prerequisite. From the Cambs site:Ideally you should:
- have at least two years' full time (1,200 hours) experience of teaching English to adults within the past five years
- have a range of teaching experience in different contexts and at different levels
- be a graduate and/or have an initial teaching qualification
- have a standard of English which will enable you to teach at a range of levels.
Centres may still accept you if you do not strictly meet all of these requirements but can demonstrate that you would be likely to complete the course successfully. This is entirely at your centre's discretion.
Learn more about it at http://www.cambridgeesol.org/exams/teaching-awards/delta.html
, and and preferably approach some centres to see if they would accept you.
Finally, unless you can get a job in Taiwan, Korea, or Japan (Alex can give you more details), it is common knowledge that EFL eaching is not well paid unless you can climb the greasy pole to becoming a Director of Studies, but for that, you would almost certainly need a degree.