Transferring from Faculty of Arts to Faculty of Science in McGill University

Hey, I am an international senior high school student, and I have been accepted to McGill University. However, I got accepted to the Faculty of Arts while originally I wanted the Faculty of Science (specifically the Pharmacology Undergraduate Program). Apparently, I got rejected from the Faculty of Science because I haven’t met the prerequisites for the course.
If I were to attend McGill’s Faculty of Arts (I am thinking of choosing an English major for the first year), will I be able to transfer to the Faculty of Sciences from there or will I be taking a risk of staying in college for an extra year.
My counselor told me that in Canada, for undergraduates (especially the first couple of years), the courses are not major specific. But I just wanted to make sure: will I be able to take the necessary prerequisites for the Pharmacology program in the Faculty of Arts and then transfer from there? Or should I exclude McGill from my options for college?
PS: I applied to so many places, and I got accepted to Rutgers University New Brunswick, King’s College London, UBC, and University of Sciences in Pennsylvania.

Any help would be greatly appreciated since I have to make a decision of where to go to college very soon. I am panicking because I have my IB exams in less than a month, and I would like to get the college decision out of the way as soon as possible.
Thanks a lot in advance.

You can apply to transfer from arts to Science near the end of freshman year, but it is competitive.