sixth forms hellpppp

basically i applied to 2 selective sixthforms (latymer and dame alice owens) and they both declines me. its the point now where all deadlines for applications are closed so its too late to apply, but i really want to leave my current school because i am so unhappy there.
does anyone know any good sixth forms / colleges in north london where i can study physics, maths, and design technology a level? im predicted 9s for these so grades arent the issue.
thanks xxox