Is leaving school and switching to private a good idea?

I was abroad for a while before returning to my home country, and due to differences in the teaching styles, I am one year behind in a few subjects. Currently, I am in Year 9, but three subjects are completely new to me, while my classmates have already studied them for an entire year. I'm finding it challenging to keep up with what they have learned, what they are currently studying, and the frequent exams given by the school.

Additionally, it is common in my country to attend coaching centers, as schools often do not prepare students adequately for these exams. Now that I’m halfway through Year 9, I am considering whether I should leave school and join a coaching program for the next six months to prepare myself before returning to school in Year 10. I’m concerned because in Year 10, there are monthly mock exams, and it may be even harder to catch up if I don’t act now.

Any suggestions?