applied for a job which is not my career progression - move sideways... feel a bit bad

[startnow]

feel bed in my ambition - but need a fresh start/environment to build up energy for the next post. or part of me thinking why not to be patient and wait for a better post and decline an offer that I have now?

You're doing exactly the right thing, I reckon.
Apply for promotions when you're feeling confident and have the zest back. A sideways move is nothing to be ashamed about.

I've done that, to get experience in another school. Good for me, I think.

I've 'demoted' myself a number of times over the years. Sometimes I can't comprehend what I used to do (in very senior roles). I really, really love being a highly experienced and well qualified teacher in a non-management role, despite the paycuts I've taken. Some of this was out of necessity - it was very hard to find part time work in my field after DC and relocation - but has been for the best in every way.

No need to feel bad. I've been in the same school for 10 years (minus a bit of mat leave) and I love it there but have no inclination at all to be senior management. I've done a number of Middle management jobs and have really benefitted from the experiences I have had. I love being one of the "old" timers at the school and have explored both curriculum and pastoral roles. I have been able to see where my passions lie and have been made an SLE which suits me very well.

Up is not the only way!