Apply some risk management thought to your scenario. Are you competent to do what you have volunteered for? i.e. do you understand the hazards that will be created and the risks they present? Do you have sufficient knowledge and skill to be able to suggest additional controls if these are needed and then assess whether they are adequately applied? Who will have the authority to say "No, you need to do it in a safer way". Is there an organising body that has purchased liability insurance? Then consider how likely it is that you will make a bad error or omission that then directly allows a dangerous situation to occur and then harm to be caused, without any other intervening party? If, at the end of all that you are still frightened about being personally sued, get someone else to do it.

Don't be put off! Your qualification and experience readily allows you to identify and quantify the safety risks associated with a village event. You should inform the event organisers that you will be simply advising them, and it is then their responsibility to follow it through. Anyway, in my experience, safety professionals often tend to go "over the top" with such advice, just to be sure they cannot be "held to account". You can soon tell if a safety professional has been involved by the sudden proliferation of "high-viz", and "taped-off" areas. Rural people are much more tolerant of risk than the urban population, with many rural events having a very long tradition. They are often organised by a small core of long-term volunteers, with the same sort of scenarios occurring every year, with everybody knowing everyone else, and with the whole village turning out. Good idea to have a look at the HSE guidance, a little dated now, but is the current version until the new guidance is produced: http://www.hse.gov.uk/event-safety/index.htm Also have a look at country shows, garden festivals, and village fete websites. Good luck!