I can't help with an interview concerning the theoretical part and questions, but I can share with few psychological tricks on how to feel confident before an interview. Firstly, look for (there are plenty of sources in the google) confident postures, they'll help to gain confidence before any interview. Next, mentally train yourself before the interview i.e. write down all the possible answers to the questions, you can also search for the potential questions during this kind of an interview. Wish you luck.