My wife and I are experienced cruisers and this was our second sailing with Princess. We were really excited about this particular cruise because for some reason, this was the only sailing offering this exact itinerary this year and next. We flew into Gatwick and took the Gatwick Express to Victoria Station and then took the underground [tube] to Earl's Court. We arrived a day early [July 20th] to experience London.
HOTEL AND LONDON: We booked a room at the Earl's Court Comfort Inn online before our departure. A couple of things to bear in mind about London. First, many hotels do not have AC, which is something we pretty much take for granted here in the US. We arrived in London on July 19th and were told it was the hottest day in recorded London history. We also quickly discovered that London is a very expensive city. A simple sandwich and drink at the pub across from our hotel was 7 pounds [almost $14 US]. Still, we had a great time in London. We were able to visit Buckingham Palace, Big Ben, and Trafalgar Square just to name a few places. We even saw a show at Covent Garden [of My Fair Lady fame] that evening. My final piece of advice about London is as follows. Do not bring heavy bags on the tube. It is not designed for this and you will have a hard time. Escalators seemed to be a rare luxury.
TRANSFER TO SHIP: [Southampton] We did this on our own, taking the tube as far as it would take us and then grabbing a taxi from there. I don't remember where the tube ended, but for the reason listed above, I would discourage this option anyway. When we researched this before the cruise, we thought the ships prices were too high. We did not realize just how expensive the UK is, and I think we would have been better off using the ships transfer service. Southampton seemed like a nice town in its own right and we would have liked to have seen a bit of it had time permitted.