i really doubt they will refuse you if you are polite but firm about it.
I sent an email before my name change, and before T to my sexuality teacher (because I knew he would understand)
I said something like..
"Hello Professor. I am going to be in your __ class this coming semester and I just wanted you to know that I am a female to male transsexual, and although my name has not yet been legally changed, I would like to go by Elijah. I would also like to be referred to with male pronouns, I just want to be treated like any other guy in your class, thank you and see you in class."
He was awesome about it always calling me Mr. (last name) (even though I didnt pass)and he paired me up with all guys for a project we had to do.