POST SECONDARY QUESTIONS, PLEASE HELP!!?

I'm finishing up my grade 11 year at the moment. I would like to become a nurse after highschool and educate myself in that direction. I would like to go to BCIT or UBC for the nursing program. BCIT definetley looks at your gr 11 marks and unfortunatley I did not do that great this year. They look at your chem 11 and math 11 marks for admission into BCIT. Unfortnatley I'm just passing those courses and I won't be able to get them to a C+ or higher. BCIT requires you have a C+ or higher in math and chem 11. Since I do not meet that requirement I was thinking about re-doing chem 11 in summer school and math 11 during my gr 12 year. UBC strongly reccomends you take chem 12 but if I just passed chem 11 and I do not fully understand chem 11 how will I be able to take chem 12? That is why I want to re-do these 2 courses. Also, If I do not get into UBC, I want to be able to get into BCIT as a back-up so if I do not get into UBC atleast I will be get into the BCIT nursing program. Do you have any suggestions? What do YOU think I should do? Will re-doing these courses help me in the future? Is this a good idea? And I know it will require a lot of effort on my part and also a lot of time in the summer but I really want to get into this program, I do not want to waste my time after highschool upgrading these courses..