Thanks for the question :)
My personal motto is. “It’s better to be over prepared, than under.” I would suggest having a couple chosen. With the first audition they only request two contrasting (contemporary and classical). But at the callbacks, as far as I know, you are required to bring one additional monologue.
I was personally intimated by the classical pieces, so I made sure I had a few contemporary in my back pocket. Hope this helps.
Surprisingly, a lot of student who come to NTS do not have professional experience! You are not alone. I think that this sounds fine, use people that you trust and can speak to your strengths as an actor/actress. If you have any other questions don’t hesitate to message me :) Best of luck.