As Sector one is (fairly obviously) the area from the Grandstand out past Quarterbridge, this would be the most suitable for paddock-based volunteers. Either that or Sector 12, which is also close, but in the opposite direction, heading away from the start finish towards Hillberry etc.
However, when you go to sign on, you will be asked what you prefer, and you will not be sent up the mountain if you need to be back for the children etc.
Transport is available to take marshals out to their posts, as long as they are ready in time.
All these concerns will be addressed if you pop into the office and ask the nice people there. They deserve a mention for their hard work and patience.