Question for The Montessori Education Center

I am a year 12 student in the Cambridge system and I am doing Physics, mathematics and Geography.
I would like to have my final year in a different system specifically Montessori. I would like to join in at Grade 12 .
We have closed our year of year 12 in Cambridge
So is it possible for me to join in at grade 12 and if so any information provided will do me good