If you're worried about what to say or how well you'll do, etc. I would take a couple of the basic courses at a local community college, see how you do and then transfer; then there won't be any questions about your age or health or that you're older or anything else at all.

Another route is to enroll in an accredited online university (I went to the University of Maryland University College http://www.umuc.edu/index.shtml ) where it is all adult students and you don't have physical classes at all and no one cares about your past, they just try to help you do well now.