In reply to Lizzie:
I'd say both have their pluses and minuses. Understanding some of the theory behind why children behave like they do can make you a better teacher. Yes the GTTP course is paid (but so is PGCE now), but if you end up with a school sponsored one the school can basically treat you as a member of staff, so the extra free time you're meant to get as you're learning the job can disappear. I know a few people who left because they just couldn't cope with this.
To the OP- definitely look in to it though.