Congratulations! At stressful times like this, I would engage a florist to do this for you. Sasanquas are in bloom around October and late blooming Japonicas are in bloom in the Souther Hemisphere. You can try to check Dr. Ackerman's hybrids for nothern climates. They bloom early. Mother Nature can be iffy so it may help if someone else is in charge of this.

I don't know of any japonicas that are blooming here in october but luis is correct in that fall is sasanqua flowering time in the u.s. those that i am familiar with are short on substance when compared to japonicas and tend to shatter very easily. there is a process in which camellias can be waxed to extend the life of them but you probably don't want to get into all that. i have never seen any cut camellias in floral shops, either. they are just not the best cut flowers for endurance.
the silk one at the link below sounds like your best bet.

Here is a link that might be useful: camellia hairpiece

I agree that a professional should be consulted about this. Such a person can advise you should camellia not be a good choice for this purpose. But if it can be done, the professional can also design and make the hair piece for you.