I'm one. I love it (mostly...)! It's a supportive, interesting, useful, intellecually demanding profession. I wouldn't want to do anything else (except for the odd day, when I'd do just about anything else!)
In answer to your questions...
Trainees are getting younger I think, that might be to do with the 'new' training arrangements. When I did my training, about 6 years ago, we were a varied bunch. Some, like me, were quite young and inexperienced whereas some were really experienced (HT's, senior advisors etc). Being older absolutely won't hold you back from gettting on a course though and you sound like you have really solid experience. I think that the course tutors like to see a variety of applicants as it makes for a richer training experience for everyone.
Employment prospects is a funny issue at the moment. I don't know of any EPs who have been (compulsarily) made redundant. Know of two who have taken voluntary redundancy to set up a social enterprise. I don't know of any trainees who have not found a job, one way or another, either. And as FarSide said, there are (and will be) many other opportunities, especially in London. Most of my colleagues do some sort of private work (or research, or university tuition) on top of their LA work if part time.
From what you have said, you've got some solid experience. What I'd advise, is that you get to know the principal EP in your borough and talk to them about how to bolster your application and what sort of additional experience you should be getting (shadowing work can be really hard to get due to confidentiality issues, but you could ask your SENCo if you can sit in with her on some consulations/assessments). The courses are really competitive, but the trainees are only human (thank God!)
It's a job which is very compatible with having a young family. I have DD od 2 and another on the way. Will take a year Mat leave and return to post at the end of it. At the moment I do 0.5 contract with half a day of this from home. All works rather well. Perhaps I'm lucky as my service is really supportive of this as are HR, I know plenty of EP's who do some sort of flexible working though.
Hope that helps. Good luck :)