There was "unauthorised" information that got leaked from the German press. Basically, BP sent out an Operational note to the media. Some of the information was embargoed. They will let the press/public know as soon as she goes into labor, and then will open the grounds on the Long Walk for the Press. The grounds will be open for 3 days.
A few days after birth, 1 PA photographer, 1 PA reporter and 1 camera will be given access to the couple on the grounds of Windsor Castle.
Again, all of this was embargoed, but it got "accidentally" leaked on German news program.