I would go along completely with what
hatler says but pick the training provider
very carefully.
However there are now over a dozen and not all keep to the same methods or high principles of delivering the instructor training and some have watered it right down to be
very questionable.
Be aware that some instructors have also reported to have had difficulty with the follow up mentoring from some of the providers.
The full list is here:
Cycle TrainingBe aware too that you will need to jump through a lot of bureaucratic hoops if you wish to deliver Cycling England's Bikeability brand.
Not all instructors do, or find it necessary.
All that said it is a very enjoyable occupation with some terrific experiences. With some lateral thinking the opportunities are quite wide ranging.
I've been training nearly five years and whilst it is very seasonal, last year ran over 2000 trainee sessions. That was already beaten by May this year.
Even so, financially it is not that rewarding.
FWIW I can fully recommend
LifeCycle in Bristol.