That's absolutely horrific to hear, stuttering is normal and there's nothing wrong with getting a helping hand. When I first came into the school, when i introduced myself to people I would just say ' Hi I'm A-a-aron, sorry about that, I have a stutter that's all'. I never had an issue making friends, when i got to know people more it was a breeze talking to them. The 5 minute conversation you have with your principal will lead to many years of not being worried in school. I would just say ' Hello Sir/Madam, sorry to disturb you but I'm just wondering if you could let the other teachers know that I have a speech impediment and for my own comfort I would prefer to not read out in front of the class' - that's just a brain storm for you, I would alter it to words that I know are easy to say for me and that I can get out. Best of luck, let me know how it goes if you do anything.