The rule of thumb is that if there is something that you desperately want to do and you do not think you can do it on your own then book beforehand.
Don't forget that people often pal up on ships and go ashore together thereby sharing the cost and friendship and, often, experience and knowledge. ..... Neil
dont need to but you can book before you go the Precruise brochure has a page where you can fill in and send off otherwise you can book over the internet which I have already dont. You can wait until you are on the ship and book then but the trips might be full.
If you are wishing to book a ship's tour then do it before you go as the popular trips may well be booked up. If you go to the P&O site you can book your trips on the Cruise Personaliser. You need to either be a member of the Community section of the site - very easy to register - or you will need to enter your booking reference to access the Personaliser section.
If you want to arrange your trips independently then you obviously don't do this in advance.
Good information but there is nothing to stop you organising your independant touring in advance especially if there are four or more of you, we have done it many times and we know the price and they are waiting at the quay for you. The internet is full of touring companies all over the world and you can get good prices but do make sure that their cancellation policy includes "if the ship does not dock then a full refund will follow". All the best tourers offer this. .... Neil.
Just have a look on the cruise personaliser on the p and o website, some trips with limited numbers get booked up quickly, so I would advise you to book these pre cruise. Otherwise you can book on board, If you book before you go you can always change your mind when you get on board.