I replied on another thread about this to someone else - I'll copy my post here, but this is the thread.
www.mumsnet.com/Talk/am_i_being_unreasonable/4373587-Being-diagnosed-with-ADHD-as-an-adult
Barkley, R. (2013) Taking Charge of ADHD: The complete authoritative guide for parents, third edition.
Executive Skills Coaching Tutoring online www.beyondbooksmart.com/
Children and Adults with Attention Deficit Hyperactivity Disorder (CHADD) at www.chad.org
Wismer, Cindy Stringer (2014), ADHD in Adults
I also found this book useful - The Adult ADHD Tool Kit: Using CBT to Facilitate Coping Inside and Out.
And this is a good read - Better Late Than Never: Understand, Survive and Thrive — Mid Life ADHD Diagnosis - Emma Mahony, Sari Solden
You could also look for local coaches, tutors and psychologists who specialise in ADHD - no idea if that's a thing in the UK, but I bet you could find some online who'd do Zoom sessions with you.
And join some FB groups. ADHD Female Entrepreneurs Community sounds like it would suit you. ADHD for Smart Ass Women is also a good one.
I also hear really good things about Focusmate, which is an online service that gets you together with other people so you can motivate each other.
Body doubling is another technique that works for me. If I work with someone else on something I do so much better.
I have started on meds and they do really help. Again if you look online at some FB groups there's advice from people in the UK on how to get assessments via the NHS.
The Calm app also really helps me.