I am really scared and nervous please can you help?

i am going to the hospital for an operation on my mouth and i have to have a tooth removed from the roof of my mouth and the piece of gummy stuff that connects your lip to your gum removed and a removal brace fitted on the top and the bottom and i have heard that before you have an operation i have heard that you have to go in the day before you have an operation so i was wondering how long i would have to be in there for and if it would hurt much when i woke up because i am really nervous and scared