What options do I have? (A-Level Student)

I’m an international A-Level student from Kenya and I’m currently considering applying to universities in Canada and the U.K for computer science. I received my final A-Level results a few months ago and got the following:
B - Math
B - Physics
C - Chemistry

I’d like to go to universities like UBC, U of T, Warwick University and Imperial College London to name a few. But as you can probably tell from my grades the chance of being accepted into any of those universities is particularly low.
I’m currently taking a gap year and I should be starting university around September to January time of 2018. Based on this information, what options do I have (e.g resit exams and apply with different grades, attend those universities for post graduate study) and what universities (both in Canada and the U.K) would you suggest I apply to (I’m currently considering SFU, Queens University (In Kingston), Victoria University, Western Ontario University for Canada and Edinburgh University, Cardiff University, Kent University, Birmingham City University and Brunel University for the U.K)?

I am considering applying to U.S as a last resort (Not really interested in studying there and I haven’t completed any SAT/ACT tests) but I welcome any advice involving applying to universities there (Note: It’s required that I enter university between September and January of 2018). Really desperate for help, so thanks in advance to anyone who gives advice.