There are a couple of ready written risk assessments Here which you are free to copy and amend as you wish. I was asked only a week or two for a risk assessment for a 'busking' type event (first time ever!), so I just wrote them! The organiser of the event just files them, (with your copy of your PLI certificate) and they only see the light of day if a problem arises.
If you are professional about playing for the public, then these sorts of things are just things you have to put up with! (IMHO)