I have been teaching Presentation Skills professionally for over 15 years. My courses are about developing and attaining your natural style in front of people. Being yourself. You are quite interesting!
The other courses out there and the organizations like Toastmasters have a different approach. I believe wholeheartedly that if we can learn the techniques that allow us to be ourselves and natural in front of people, and not by learning an "act" or "schtick" or "gimmick", we will be far more believable, confident and successful. And effective!
When people were surveyed about their greatest fears, there was one that surpassed death, spiders, snakes and losing a job. The dreaded fear was speaking in public or 'glossophobia'.
So, guess what? You're not alone at being nervous. I will let you in on a little secret, it is considered a normal reaction we humans have. This is especially true when someone asks that you speak to a group of people, and even more so when you do not know any of them. We all have that tendency to become nervous. I do not care who you are, some are just more nervous than others.