I also learned violin at school and took no exams and didn't touch it for more than 40 years, Whn I retired I was persuaded to come along to an amateur orchestra where I felt completely out of my depth in the first rehearsal. However with encouragement from other orchestra members I persisted and also had a year's worth of revision lessons with a violin teacher, and I have improved beyond my wildest dreams. I'm still not all that good, but can play most of the music at orchestra now , missing out or simplifying what I can't play and I absolutely love it - it's the highlight of my week.. I have also joined an amateur string orchestra which I enjoy. My husband also took up the trumpet again on retirement and plays in the same orchestra as me and also in a brass group. I know lots of people who have come back to play an instrument in their retirement, or even learnt a new instrument from scratch although that is obviously harder. It does help if you learned to read music as a child, but if not, even that can be overcome. I recommend having lessons though to learn a new instrument as it's hard to keep motivated when teaching yourself.