question about rescheduling a sac

next wednesday i have a general math sac (part 1 of 2 periods) and i cannot go because i am going for my license that day. we booked the license in advance before i realised i had a sac, and its been so hard to get an appointment.

i know i need a medical certificate or something to miss a sac, but i can’t really because i have to tell my teacher in advance and i wont have a medical certificate. i was going to get one over the phone but then it would be really hard for me to tell her that im not going to be here on the sac day because i felt ‘sick’

pls let me know some excuse i can use i mean at the end of the day i can just reshedule my liscence but i don’t want to if possible