Have you considered widening your options in the visual arts? I know - I hate when people say that to me (as I have widened my options to a variety of arts careers & it still doesn't help me in this Wild West mentality & backwards Colorado!!).
I'm considering the possibility of moving to London in the distant future (if it weren't for the horrible quarantine of my cats & rabbit!!) & would be interested in how your career goes.
But I would probably try to get a part time job at the Creature Shop through Henson Productions to suppliment my art therapy income if I ever do end up there.
If you enjoy working with special ed students & have interest in therapy, you can check out what your options in getting a master's degree or cert. in creative arts therapy. Attend a conferance, read books & volunteer before putting in the money & time. I imagine employment in art therapy is more viable than art education over there. From what I heard, London has similiar opportunities as NYC. In the meantime, have you looked into teaching art at residential treatment centers, day care centers, treatment programs, organisations that work with people with developmental disabilities/neurological impairments (like UCP),after school programs, etc. if jobs are limited in public schools? If you don't live in London, your options are probably more limited.
Let me know how your search goes. :-)