A good place to start:
If you are taking your first steps into learning about ADHD, one of my favourite resources is the Youtube channel:
It is presented by a very friendly host, Jess McCabe, and they are very well researched and easy to understand, and they're fun!
This list is by no means a complete list, but enough to get started, and a great support to our coaching. I am happy to add recommendations.
The team at drugwatch.com have given a good overview of ADHD: www.drugwatch.com/mental-health/adhd/
And treatment options: