We did the pre cruise London stay with transfers a couple of years ago and it worked out wonderful. We booked our own air but let Princess do everything else. We stayed at the Renaissance Chancery Court, which was really beautiful. It was a long ride to the port so the Princess transfers were the most cost effective way to go. They picked up our luggage and loaded it on a van and then we boarded the bus so we never had to fuss with our bags. There was a mix up on the arrival time of our plane and the Princess representative waited over 45 minutes until we got into the terminal. We were the only people she was meeting and she had arranged our own personal driver to take us to the hotel. We always use the transfers as they make things go smoothly and with much less fuss than trying to arrange things ourselves. Have a wonderful cruise.