I had the same anxiety about working in an office setting when I did a placement. Like anything new it is stressful, and if you are introvert and deal with anxiety it can be tough at first. But I’m sure starting university was the same feeling and it’s something that passes after time.
Also, Just make sure your prepared for the interview. Do research on the company you are interviewing with. Have your portfolio ready before hand, and practice talking about each piece, you may not end up talking about many of them, but at least you won’t be caught off guard if your asked a question about a piece.