Admission to the Faculty of Science at the University of Western Ontario from an Ontario high school requires the following courses:
and any two of:
If while in High school you know that you are going to take further studies in Physics and/or Astronomy, you would be well-advised to take Physics at the grade 12 level.
At the university level it is fair to say that 'mathematics is the language of physics.' Successful physics students almost always find mathematics reasonably easy and enjoyable.