I am old enough to be the original poster's father,being in my early 50s.
I only ever had 2 driving instructors years ago. The first one, was only a few years older than myself, I was late teens, & he was too c*cky for my liking. The second was an acquaintance of the family, & I worked with his wife. Davie I got on well with. I can still remember him saying that when you change driving instructor, treat it as if you have never driven a car before & forget what the previous one taught me. This being the late 1980s, & I could only afford lessons from my own salary, I would stop lessons on the lead up to Christmas & in spring time when I was saving my spending money for the summer holiday I was going on in the near future.
I knew how to drive, I was driving into the centre of Glasgow under my instructor with no problem. I never remember stalling on the hills. My instructor told me & my parents that I knew how to drive, my confidence held me back. I grew bored, & never sat the test.
The original poster mentioned riding a manual bicycle. I never could do that. I think I was about 8 years old when my father tried to take off the stabilisers and I couldn't do it. Too timid. The family tried again at the end of my school days, & I was too timid to let go.
I did have a bullying father for decades who never instilled confidence in me, he was a taker.
I have not looked in recent years if the 1 weeks, intensive driving courses are still available anywhere on the island of Britain?? There was at least one residential course in Scotland. No idea if it still exists or something similar?
Age never used to be a barrier to passing the driving test. Some people came back to it in their 50s/60s, though that was the old style, before this split test nonsense.
To the original poster, try not to do your own head in. Give Time, Time. Try other things & it may come back in future as something to try later?