It really depends on how much hair you want to take off. If you are only wanting to tidy up the sides you will be able to keep your undies on and just pull them to the side while they wax. If you want more off then they might give you a paper g-string, just ask if they have them. If want to go Brazilian, then no point wearing any undies at all! If you are going to wear undies make sure they are bikini briefs or a g-string, not a boy leg style.

I wouldn't say it was torture, they whip off the wax so quickly you haven't really got time to react. Maybe as a novice just start off with a "standard" wax where they will just wax off the hair that would not be covered by a bikini bottom and then work your way up. That will only take a few minutes - you'll be out in less than a quarter of an hour.

I agree with previous advice, don't get it done in the few days before AF is due, your pain threshold will be lower. And I don't recommend DIY waxing at home, especially if you think you will chicken out. Way too messy and painful and you might not get the angle right so you will get the ouchie factor and then still see all the hairs left behind!! (Been there!) Maybe it's my technique but it hurts me far less at the salon.

As for trimming prior to the visit - guess it depends on how much you've got! Personally, I like to trim, but they really don't care. I got to be good friends with my old beauty therapist and she was very much "seen one, seen 'em all." And they are very familiar with mummies that don't get to spend much time on themselves. If you do decide to give yourself a haircut, don't trim the hair to any less than 0.75cm in length. I also like to freshen up with a baby wipe before I go.

Don't be afraid to tell the therapist it is your first time!