Someone once asked...
Someone answered with kindness...
I think you're either stressed for the meeting/talking or you feel a guilt for making people wait behind you in line, when the line is meant to make people wait... in a line, yeah. If you think it is the first case: You don't know what to expect, to say, to do properly once you're next. It's okay, really normal. You say hi, and tell them why you're here. Or they'll ask you questions and you'll answer with the best you know. It's okay if you stutter or forget or change your mind mid-talking. You're a human and you can get something wrong. The service will not point and laugh and say "NEXT!!" and kick you out of the chair to let someone else in it.