Hi Bianca, thank you for your reply.
First I should clarify that I am looking for pre-university gap year schemes, which does narrow things.
Secondly I must ask, has YINI changed? In the vacancies page there are only four schemes that are relevant. Unless I'm mistaken, EDT ask you for your CV which you can update, but if you're applying for multiple schemes at once you can't send individual CVs out. There's no cover letters either at the initial stage. The only customisation is a 'in 300-500 words why do you want to do a placement' in the application form, which I do tailor.