Yes, you need to get in touch with the disability support service at the university about an accommodation. They should telll you what kind of documentation you will need to claim it, and what the accommodations you expect. However, in addition you should also be upfront --- regardless of whether you get an accommodation --- with the professor about your stuttering. This is life and when you start working you will have to deal with these issues all over again. Go to office hours and talk to the prof about your stuttering. Do it in the first week of classes.