now is not the ideal time to do what i did, but i felt exactly the same way as you did, i was a trainer working for Orange in the call centres and retail.....
Binned it and went self employed initially for the first year or two, working contract through agencies, now a days i have a Ltd company and we tender for contracts and effectively place people who are where i was a few years ago....
I still train as well, i love it, i get to work for different people all the time, there are a lot of downsides, like being away from the family a lot and the financial insecurity when one of your clients goes to the wall owing you a rather considerable sum, but i chose to do this and so i must take the risks that go with it.
James in a way you are not dis-similar to me in your style of doing things, you ae a bit of an activist (and before anyone says i don't mean BNP)by the sounds of things, likes to be in the thick of the action, normally one of the first to voulenteer for something but when it becomes tedious then you are quick to step back from it and want to move on, if that's you then there is nothing wrong with that, use it to your benefit