I got into a Top 3 engineering program 25 years ago and had the same concerns you do now. I went despite the fear and loved (nearly) every minute of my education. You're going to be in a position to meet so many incredible people (some of whom stutter, too) and get to be part of some incredible experiences. The best advice I can offer is: the only thing that separates the students that have a "basic" college experience where nothing out of the ordinary happens and the students who regularly find themselves in the best projects, discussions, and internships is the willingness to speak up and say, "I'd like to learn 'X'...can you show me?" It's not always going to be smooth sailing and sometimes you're going to feel embarrassed -- that's natural. Don't ever let fear of that stop you from introducing yourself, asking questions, or having fun. It's a low-risk, high-reward scenario where some of the rewards have the potential to alter the course of your life. Soak up every drop you can.