Ok... so the suggestion made earlier that Teach First would leave me less academically qualified wasn't correct, and the opposite is actually true?
I watched the BBC tv series where they follow 4 students fresh out of university on the scheme last night. On the one hand it makes you hate the whole thing, as obviously the students they picked to follow are entertainingly extremely posh and young and clueless, to make good tv. On the other hand, it made me think "well I am obviously nothing like these guys, so maybe I could do more good than them, and maybe the nature of the course has changed over the years since." (as a lot of the application questions I did seemed specifically designed to filter arrogant people like that out of the course).
I definitely made a decision to try for a secondary maths PGCE course with bursary... but I'll still do the teach first second stage interview, it sounds intense with a lot of practical work so that can only be a good experience, plus I've got few more questions to ask them now.