Honestly, having worked in education ever since graduating, never as a teacher in the UK - but I have worked with schools in the UK, and am constantly in contact/dealing with teachers, I would always second the recomendation of:
Try it.
To many people just presume they will both be a good teacher, and actually enjoy it.. becuase of some ******** justification of:
'Its so rewarding...' 'I am passionate for helping people' blah blah.
--
Maybe you are, maybe you are not, but there is a lot more to teaching then being passionate and finding it rewarding. No chance you are thinking 'this is so rewarding' when you have a couple of horrors ruining your well laid plans, and your tired from marking until late.. your stressed because of the huge amount of bureaucracy that goes into your job, and the crazy targets your boss is setting for you.
I would recomend to all who are interested in education to do a number of the following:
Volenteer in a school, for a minimum of a few weeks, preferably giving a bit of time each week for a whole term/year.
This will give you a good picture of school life, but it wont show you what its like to be a teacher. Volenteering will always have you as an assistant, a 2nd. To truely understand what its like to lead, and realise if you are actually any good at it.. I would say that its essential you find some way of putting yourself in a position of leadership:
For example, my sister, before becoming a teacher took over a cub group. She had 20 11-12 year old boys to manage, plan for, control etc. once a week for a year.. That was much more valuable to her then just watching other people teach, as it actually taught her and let her experiance leadership.
Mentoring younger students, private tuition, working with a nursery, volenteering at a youth centre, scouts, cubs, guides, brownies, church groups etc. all types of things that can help you experiance planning, organisation, control and leadership.
---
The problem with teaching is that everyone thinks they can do it, but actually most people cant. The good news is that it has amazing job security, so even if you cant, its unlikely you will be forced out! But seriously, anyone can get to the level of study required to teach, but having the actually ability to excel in front of a big class is something different.
There is money in the career though for the best of the best.. you just need to think outside the standard school system.. once you have experience there are lots of options open, from colleges, to private education, to language schools, international educational programs, universities, community programs, and much more.. you just need to be prepared to think of education as a large industry, and not just individual schools.