In reply to jezb1: I was chatting with a few Centre Assistants while there some while ago and it seemed that they were involved mainly with general duties and helping with groups rather than instructing but as the other poster said I think they were enjoying the experience.
The person spec is "looking to become leaders and instructors", and I see from your UKC presence that you already holf ML and SPA, so I suspect might be overqualified.
If you were looking to spend some time as an instructor a number of the magazines carry job ads for instructors which might suit you.
Good luck in finding something. Might also be worth asking PYB what opportunities they might offer for Centre Assistants who are already qualified.