So, I have beening marking student presentations in university for 3 years now. I have yet to see a criteria about 'speaking fluently'. Your stutter is very unlikely to get you a markdown. You can contact your disability services team and your lecturer and ask for reasonable adjustments, such as longer presentation time or only presenting to the maker, etc. You may also inform everyone you are a stammer, and if you didn't say anything clear, they shall ask you to clarify, but they need to wait until you finish the sentence. I say this to my students when delivering classes. Everyone's condition is different, so there is no big red bottom to press. Don't treat the presentation as a challenge, considering it's a practice for life skills. However, I don't have a problem with presentations somehow, so take a pinch of salt. In many countries, stammer is a protected characteristics so you shall get support from your uni instead of dealing with it yourself.