A bold gesture, Mr Moss and to be applauded, but, although I rarely agree with Matt, he has struck a chord and whether you are offering something FREE, or otherwise, we are living in a sad world, with litigation issues appearing from the most innocent of actions.
I would look seriously at some form of indemnity, or disclaimer, to protect you, because, with the best intentions and while trying to avoid endangering people, or property, THINGS DO GO WRONG.
Unfortunately, it's usually to person who is doing the favour, who gets clobbered.
We are involved in training activities in our Care business and the legislation / monitoring / reviews/ compliance procedures are getting worse by the year.