medicine insurance choice help

hello! i am trying to decide between firming a medicine offer at one uni and a medicine with a foundation year offer at another. i think i want to firm the regular course and insure the foundation course, however i have a feeling i may regret this and end up wanting to go to my insurance choice. if i exceed the grades required for the foundation course (they want BBC, if i get ABB/AAB) but also meet the grades for my firm choice, and end up wanting to go to my insurance, what do you think the likelihood is that i could call up my insurance choice on results day and ask if they still have a place available for me? i know unis get your grades before you do so technically my insurance offer will have already been cancelled by results day, but if they have a place for me as my insurance choice then surely they will still have room for me on results day? i'm just wondering about the likelihood of this being able to happen in case i do regret my choice, as i know medicine tends to be much less lenient than other courses