I felt exactly like that. As a matter of fact, I still feel that way (I start on monday)!!. I think it's normal....Like the OP said, I wouldn't trust anyone who walked in there as if they knew it all otherwise, why would they be in school?? They will teach us everything we need to know...trust me, a few months from now someone will have a question or need help with a care plan and you will be rattling off medical jargon as if it were your first language...and hopefully I will too!!
Good Luck!