My insurance brokers got after me twice (after I ignored them the first time) to get commercial vehicle insurance, because they know I'm self employed. This is simply driving myself in around my locality in my personal car (i.e. not owned by my "business" or anything), to work on people's computers on-site.
The second time I took their advice. I was just planning on lying if I got in an accident, "I was on my way to McDonalds" or whatever, but since they were already aware of what I do (and contacted me again about it with stronger admonishments), it was sensible to just upgrade insurance.
The bottom line is, I would not be insured if I got in an accident if they could prove I was on my way to a gig.