Try not to worry about a month and a half from now. Take it day by day. And don't feel bad about leaving the physio place. It isn't full-time, right? And you need FT. If one dental job doesn't work out, you'll eventually find one that will. And you'll probably be as fond of the clients in a new office as you are of the clients in the physio place, because you're a warm and friendly person.
I understand your misgivings. I'm a worryer, too, and I like stability and familiarity, and sometimes I freak myself out over change. But I've learned it does no good to worry about things that may not come to pass. So take it as it comes, and try to view the change as a positive one. Learning new skills is never bad, and even if you find you don't like where you end up, it may lead you to the place you're supposed to be. I guess what I'm trying to say is...Perk up, little teapot!