What are my chances? Be realistic.

A Level reports and predicted: AAA
AS Level grades: BCCD, I am redoing my AS Levels and am most likely to get AAAD.
IGCSE: 5 A*s and 5 As.
ACT: 30+
SAT 2s: 750+ on all 3 SAT 2 subjects.

What are my chances of getting into McGill?

http://www.mcgill.ca/applying/how-we-make-decisions/minimum-grades-used-admission-previous-years/al

The lowest grades I’ve seen people get at my school and get an offer is ABBB, everyone lower has gotten rejected, id recommend you apply using your SAT2 and ACT score and ignore GCE.