Yeah the DVLA is a complete fucking mess.
As I understand it, you used to have to declare ADHD, but the rules changed years ago so now you only declare it if it affects your driving. So if someone tells the DVLA about ADHD the DVLA assumes it's because they are unfit to drive as a result, because you are not meant to declare it otherwise.
As you said though a lot of people are under the false impression that they're expected to declare it by default, and this is when people lose their licenses and get in a mess.
Best thing to do is not tell the DVLA shit. Get your GP to wrote a note about the meds you're prescribed so if you're ever given a roadside drug test you have evidence of medical use. In 99% of cases this should be fine unless you're involved in an accident and there's any reason to suspect reckless driving due to taking more than you're prescribed etc.
Personally I did most of my lessons and my test on dex so I drive on dex. I do concentrate a lot better when my ADHD is medicated.
Finally you know what's funny? When that daft drug driving law was being written up, they initially wanted to exclude amphetamine as a banned drug because it improves concentration. After a few consultations between the government and the medical community they decided on a special limit just for amphetamine that is way higher than any other drug covered under that law (usually the threshold only excludes accidental exposure).
Explains changes to drug driving law and the guidance available for healthcare professionals and users of prescription medicine.
www.gov.uk
You'll notice that amphetamine as a "separate approach to balance its risk."
