I was diagnosed at age 37 when I went to see a therapist for another reason. After speaking to her for a while and going through my childhood experiences she through out ADD as something we should talk about. She recommended “Driven to Distraction” by Edward Hallowell, M.D. I will tell you there were a lot of emotions and quite a few tears during that read.
Ironically, it was one of the few books in my life that I have been able to get through without stopping.
What to expect really depends on what course of treatment you choose to follow. I chose medication and therapy, but there are all kinds of options. The biggest part for me though, was getting the diagnosis to begin with. To find out that I really wasn’t just inconsiderate of others, or didn’t care about other people’s time. Being able to identify reasons for most of those things I routinely got in trouble for as a child was really eye opening and liberating.
What ever treatment route you choose, I would recommend some type of therapy to go along with it. At least for awhile until you get your bearings with what behaviors are being influenced by the ADHD and what you can do to mediate the negative ones.
Good luck, and keep pushing ahead.