While not specifically programmed with stuttering in mind, I had a fair bit of success with the local ToastMasters club - the one I joined may have been unique as about half the membership spoke English as a second or third language, but it was a very welcoming and supportive group. People were so eager to help and offer positive feedback and they can even partner you up with a mentor for one-on-one support. I even did a 5 minute speech about stuttering for one of the projects. It's pretty cheap for a year and you get to know everyone pretty well in a couple of months. It's always free to drop in on a session to see if you like it. One thing that is helpful is that you receive a hearty standing ovation after completing your first 3-5 minute speech - I found that empowering and uplifting after my first speech - they see and support people from all walks of life and differing abilities to speak.