Student Exchange Programs

hi.
i’m trying to become an exchange student. but i have no idea where to start. Are there any programs with scholarships i can apply to?

I’m 15. i’m not sure of which country to visit. so if someone can make some suggestions.. (only European countries please).
i’m thinking about either england, spain, france, or germany.
i’d like to go during the summer only. but i’ll explore any academic year/semester programs too.

i’ve looked through some sites but most of them seem to be past the deadline for applying. i hope i’m not too late.
thanks