Mental preparation

In a few hours I'll be getting up and going to work like a normal person.  Still nervous and a bit anxious.  How much should I know?  How much do I know?  What exactly will I be doing?  Or will they expect me to know nothing?  And is that any better?

So tonight's preparation is... a bath and spa (with the bubble machine).  Have set my alarm, and checked it twice.  Suit is sitting out, new shirt, slightly doubtful tie.