I hate when I get all worried and then find out I didn't need to be because what happened wasn't like I imagined.

Can you call and find out if it's a guy? Knowing a bit helps sometimes. Do you remember your first session at other clinics? It's always scary for me meeting someone new, meeting a new therapist would be that much scarier. I have different sorts of problems with people of each sex so would probably be just as scared but "differently" depending on if it were a man or a woman therapist. If I were you I'd try to remember what they asked/what you answered today so you'll have some idea of what you'd like to make "clearer" or what he may know or want to know, where you might want to go on your first session with him.