You need to wear what will establish you as a male danseur, usually tights and a t-shirt. Many beginning classes for adults allow whatever, but your training in ballet is to establish yourself as a male danseur, not as a female dancer.
The uniform is important. Wheter or not you get to dance the role of the Prince Charming, as a male in any ballet class you need to separate yourself from the females and get the teacher's attention to show you the unique training a male danseur needs. If your teacher only teaches you the basics, without giving you the traing of a male danseur, you need to find an additional class to learn the male danseur's unique steps.
balletboy[/i]