Changing from Firm to Insurance?

Both my firm and insurance choices are at Nottingham, with a joint honours as my firm and a single as my insurance.
I've been thinking about my firm and insurance options I think I'd rather study my insurance choice than my firm choice. I was just wondering IF I made the grades for my firm choice, whether it's possible to change from my firm to my insurance?
If so how do you recommend I do this? Using a clearing hotline tomorrow, or a different number or waiting until a later date?

Normally the answer to this is no, if you meet the conditions for your firm choice then your insurance choice is gone. You don't get to choose.

However, as they're both at the same uni, it may still be possible. I'd try to contact the department directly, or failing that use the Clearing hotline. Bear in mind as well that even if it's not possible to switch tomorrow, it may be possible to switch later on, such as shortly after the course starts or after first year.