Re: nappy cob
Before I start please dont hit your horse for the behaviour, there will be a reason and hitting her wont get the desired result!!!
It may ba badly fitting tack, if she's bin out of work her shape will have changed and so the saddle wont fit, try to get it checked better safe than sorry!
If she has done it and you have gotten off, she will see this as a reward for bad behaviour. I'm not saying you should stay on when you feel unsafe!thats the last thing im suggesting, but how about letting someone more confident and/or experianced to try and see if she does it with them.
You dont say if you have lessons on her, I would defo reccomend it, Its fab for regaining confidence, and if an instructor sees what she is doing they will be able to offer advice.
Do you have any idea what could have caused it?If she is unfit be careful not to push her, this will make her less likely to want to be ridden, and she's found a way to stop herself being ridden!
If none of this helps try a wip wop rope, lots of people say these helped with their nappy horses, www.intelligenthorsemanship.co.uk go 2 sales, then tack, then giddy up rope, it gives u an explanation of how it works etc.
Sorry for the long post, hope it helped!