Log into your cruise personaliser (you just need your booking number) on princess cruise.co.uk your excursions should be ready to view there. There is also information about each deck on this site. There are also other cruise forums where passengers have commented on the tours. Hope you find this helpful
You can book your excursions (and spa appointments) using the cruise personaliser on the Princess website. I would strongly recommend booking online before you leave. I've done this on every cruise I've been on as it gives peace of mind that you have your place on an excursion, especially if it's a popular one.
The shore excursions deck can get very busy and usually only have two or three officers working at it at any one time. Also, I've boarded and found that the excursions I've booked on (and those that I haven't) have been fully booked before the ship set sail because lots of people book online.