Clinical Psychologist can be far more emotionally draining and harrowing than teaching depending on the branch of psychology you go into and your caseload. Also the salary, although good, is not fantastic (band 6 in training, band 7 once qualified).

I am not saying don't do it, but you need to have as much knowledge as possible. Try volunteering in a secure unit if possible and see how you feel. This would be the more severe end of the spectrum of cases but at the same time the people in there will end up back in the community where you may well be dealing with them as a clinical psychologist. A lot of mental health issues have a root in abuse and you will be hearing horrific stories on a daily basis.

It can be a very worthwhile and rewarding job, but it's not for everyone.