It's a question of whether the story is about you or the people around you. If the protagonist is based on yourself, you don't need any written permission because it's your story, your perspective. If it's somebody else, you can probably base material off of them. Just don't outright reference that the character is the person. I'd be more worried about offending the people than getting agreements on paper, because it sounds like you are in a situation where you don't need written permission. I know that when I do a script about myself and people around me, I ALWAYS give a copy to each of my friends and tell them exactly which characters are based on them. I also tell them to take everything with a grain of salt because it's just a movie. They usually find my caricatures of them pretty humorous, though. Always give them advance notice.