We had a crash on a trial lesson a few years ago, only very minor injuries to customers involved. They later got a no win-no fee lawyer and the club insurance handled their claim on behalf of both the organisation and the instructor.
That was a while ago and other brokers/underwriters may take a different position nowadays, not sure what the current policy actually says and I don't have it to hand.
If you do any freelancing at all, that is, outside of a club environment, then you certainly should seriously consider having your own cover (especially if you have any assets). Although you won't be doing any of that while you are initially restricted.
would a flight school provide the necessary cover you need to.....take children/elders on trial lessons?
Why do you think that the age of the participant is relevant with regard to insurance cover?