The first thing that you should do in your presentation is that you ask them to be patient as you have a speech impediment. I promise you they will only respect you for being open about it. If you can get it out in the same sentence, also remind them that your speech impediment does not affect your ability to be a good programmer. I know this is a lot to say but the ride will be smoother when the people you are speaking to are informed about what you're dealing with. After the presentation is finished you will feel such a tremendous feeling of accomplishment. And the weight of the world will be off your shoulders. If it makes you feel better I have a very substantial stutter in the form of blocks that keeps me from communicating fluently. I had an online job interview a few months ago for a sales position and I had to sell the fact that my speech impediment didn't affect my work ethic and my ability to truly communicate my ideas. I ended up getting the job no matter how many blocks I had to fight through. Good luck. I truly believe that you can do this, and accomplish all your goals despite your blocks.