I'm somewhat surprised that there are dojos out there that don't teach breakfalls. Probably means I need to get out more. At my dojo we learn them in the beginner classes. Our sensei splits the class into those that still need to learn rolls, those that know rolls but that are learning breakfalls (this is the group he handles personnally) and the rest of us that already know how to breakfall (we do breakfalls nonstop for this section of the class).
I think the points about communicating with your partner if you feel uncomfortable with a fall is important, but remember to do it at an early point in the practice, some techniques can send you flying before you have time to think about it! This would be particularly true for someone with a medical problem, never assume people are going to ask you first whether or not you can breakfall.