My oldest niece is getting set for college. She's decided to go into teaching, and has picked out several colleges and universities to apply to. Still, it is a nerve wracking time. All of the schools she has picked are a fair distance from home. I gather that she is already upset about leaving home, though she doesn't leave for several months.
She will do well enough in school, I think. Eventually, she will even come to accept being away from home. It's a question of adjustment.
I think the best advice I can give Steph is to look at the final result of her education, the profession that she has chosen. She has yet to decide what to do with that education anyway. Does she want to teach in high school, or little kids?
As for leaving home, it will always be here for her. Her aunt and I are only an e-mail away when she needs to talk. There are plenty of holidays, and we do expect her to come home every chance she gets. That's the college tradition. You come home once a month and bring all of your laundry with you.
Change is a hard thing to deal with, and the big changes often start to affect you long before they ever happen.
My mother-in-law's move and my sister-in-law's new place are prime examples.
Take heart, Steph. I am going to be a constant, mostly lacking the energy to be anything else.