I've been invited to play background music at a fund-raising dinner to be held at our church in November. Being a function of this sort it will be a set menu and I expect everyone to be eating at about the same time, unlike at a restaurant where people come and go all evening. My request is: how much material should I prepare, ie how long should I expect to play; and what advice about breaks? I notice that in restaurants the pianist/etc takes a break now and again, but I've never noticed how long between breaks and how long the breaks themselves are. Any advice?

Thanks,
Mike