I don't think there's another way to access it.
I actually had about a 7 year wait between diagnosis and medication (for long, boring reasons, also not in the UK) - during that time, I did a lot of reading and learning about ADHD and I started to try and notice patterns in my life which were causing me problems and just be aware of them. I found this was actually quite a helpful approach. It meant that by the time I started medication, I already knew what to expect, I didn't have unrealistic expectations of what it was going to do for me, and I knew what I wanted it for, which meant I was better able to feed back to my doctor during titration.
Russell Barkley came up a lot and I have found his lectures about ADHD incredibly helpful. He has what he calls this four step model of treatment/management. The first step is diagnosis, so you can check if it is definitely ADHD and whether there are any other coexisting conditions such as depression, vitamin deficiencies etc which might impact on it or make it worse and you can treat these too.
Then he has the second step as medication and the third step as education. But as I said, I (accidentally) reversed these, and I would in fact recommend this as an approach.
The fourth step he has is accommodations - which is making changes to your environment in order to support your own ADHD. I think he's right to have this in fourth. Medication is not an instant fix, it takes a while to settle into it (it took me about 9 months, though I had some weirdness with how I approached it initially). It makes things a bit worse before it makes them better. Having the background knowledge was really helpful, also the more you learn, you will find that you naturally change expectations, do things differently etc and these are all forms of accommodation too.
Anyway these were useful resources I found for education:
So You Mean I'm Not Crazy, Stupid or Lazy?! - Book - good starting point if you don't know much about ADHD, a bit too basic otherwise.
How To ADHD - Youtube channel. She also has a book.
The ADHD Adults Podcast - UK-based podcast (A lot of ADHD resources are American) - ranges from basic topics to more in depth ones. I really like this and think it is actually accessible at any level but maybe if you want the basics, begin at the start. I think this has a great mix of funny and factual.
Russell Barkley - he has a book, but it's a bit dry - I recommend his YouTube channel. This is a bit in depth and it can help to learn the basics from somewhere else first. Avoid the research summaries unless you feel totally saturated with knowing "everything" about ADHD. What I have noticed is that if there is something useful in one of the research summaries, he does a much better and more comprehensive video about it a few weeks/months later, so you can skip the summaries unless you are a professional working in the field. As a layperson, you're generally best off watching/listening to his videos on specific topics.
Understanding ADHD Open University course - this is free and you can go through it at your own pace. Really good for getting a decent theoretical grounding. It is less practical because it's aimed at a wider audience, including e.g. health/education professionals and parents, not just adults with ADHD. But good if you would like something from this angle.
The MN threads for support, any online support group, reddit, Facebook - though beware some of them are quite chaotic. If you can find a local support group in-person - fantastic!!
ADHD Essentials podcast and FB group - great practical podcast especially from a parenting-with-ADHD perspective.
If you struggle to focus on audio (I do) I would recommend doing something practical with your hands and eyes that does not require decision making. For example, folding/sorting laundry, cleaning the kitchen or bathroom, going for a run or walk for exercise, or listening while commuting somewhere.