Lower the seat limit

Is there a way to lower the seat limit in bookings down to one? We would like one person to book a time slot for training then they can share that link with their team. We don't want multiple people booking for the same time slot due to different customer databases. The training we provide is specific to the one database so we need one seat for each time slot currently the lowest limit is down to two and this is causing an issue. Also, is there a way to customize the message that is sent out? We have some instances where the booker doesn't have access speakers to complete a Teams call.