Having both work and hobby revolving around computers I can’t relax with a book. Which activities for winding down in the evening would be the easiest?

An early evening nature walk does wonders! If too late or inconvenient to do that, a short mindfulness meditation or listening to chilled music is great too

If living with someone, having a little chat with them might help. Otherwise, I find it helpful to stretch a bit, have a hot shower before bed, and close my eyes and concentrate on my breathing.