Hi Joanne

You sound like a very experienced and knowledgeable person with a great deal to offer.

Scarily enough, You don't actually need a singing teaching qualification to start teaching. Many private teachers have perhaps less experience than you do. If you were to get work in an FE College (teaching BTEC, HND, HNC) you would be employed on the evidence of your professional experience, and could work towards a teaching qualification while you taught. This would be a Cert Ed, and it's a good way to come into contact with educational ideas. Also the course fee would be subsidised by the college concerned.

The Associated Board also runs what I understand is an excellent course for teachers in private practice -
the Cert ABRSM. This is expensive but I hear good things about it.

Vocal Process also run training courses for teachers. I don't know who validates them.

Good luck with it all.

Agnes