I went to Sixth Form somewhere different from my lower years of school and in general people will bully you a lot less and have more sensitivity about such things. I found that people had more patience for me and the classes themselves felt more relaxed because everybody actually wants to be there. You will also be studying exclusively things you are interested in so you will feel a lot less stress when you are speaking. I remember being terrified on the first day, I cried because I didn’t want to repeat the same cycle for another period of my life. In my mentor period, i sat in complete silence by myself but, in every class, people (admittedly only girls actually) approached me because they saw that I was shy, there was an entire group who all had at least one class with me and they went out of their way to be nice to me because one of them was in the same mentor group as me and thought I was anxious (because I shake). I won’t lie, I am an adult and I still feel completely terrified to even have the most mundane conversation. I tend to avoid people entirely whenever I can. Regardless, I can say that college/SF was the most pleasant environment I have experienced in regards to being both disabled and having a stutter. Good luck!