As a working volunteer there is very little you "must" do but you are required to be a member of the Bluebell Railway Preservation Society (ask at station booking offices) and you must sign on before starting work each time you arrive. Both of these are to ensure that you are covered by the railway's insurance. There is also now a requirement to sign off duty as well.
At Each Station, the signing on point for the station is in the staff room in the station house.
For the Carriage & Wagon Dept. the signing-on book is kept in the workshop on the lectern next to the mess room.
With thanks to Malcolm Roe.