Learnt Latin. School did not offer this, but I could have at least looked into it, or borrowed something from a library.
Done Biology at A Level, instead of Psychology.
Or instead of History. Or done more History. Also Art.
Studied something horticultural at uni.
Or English Lit. No? Could have been fun, could have been disappointing. Could also have been useful, if I was working in something literary, which I’m not.
Learnt to play the cello. And the banjo.
Obviously it’s too late to do any of these things now because now I’m old and my brain is mush, innit.