Starting Arduino, but no micro-controller programming skills

I’m an experienced electronics hobbyist but have never learnt PICS/Micro controller/Arduino/etc. I’d like to remedy that and get stuck into Arduino. But even after a fair amount of research I’m still unsure about how best to achieve this. I have a shed workshop crammed with components, albeit mainly ancient. My hundreds of finished projects typically use CMOS, TTL, linear (555/741/etc). However, apart from a little VBA (for Excel), my last proper programming was over 40 years ago.

So I...

Starting Arduino, but no micro-controller programming skills