We are also sailing the Sept 2 British Isles. I was trying to convince hubby to stay on for the 11 night Transatlantic. I got a big fat no!
We just came off of 13 nights yesterday and he said that was long enough, and that couldn't take all that time from work at once

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But we did do a B2B for the first time. Of course the first time we do one, it goes less then smoothly.
1. We didn't receive a letter the night before as we were told we would. So at about 10 pm we went down to Guest Services and talked to someone and he said, "wow a lot of people are not getting their letters tonight". Great, just our luck. He tells us to meet at D Lounge at 9:30am and we will get instructions.
There were probably 50 people doing a B2B this go around.
2. They come into D Lounge at 9:30 and take our Keys to the World Cards and say they will swipe us all off and as soon as all other guests debark they will bring us down and then bring us right back up. Well there were some slow moving guests, it was way after 10am before they had everyone off the ship. I think they announced final debarkation at least 3 times over the loud speaker. They finally bring us down and we are at the check in counter and yes of course, the computers go down.......UGH again just our luck. We all stood around for at least 45 minutes before the computers went up and we all were set up for the next cruise. I am sure the people waiting outside to get into the port were less than thrilled, because they weren't allowed in till we were taken care of.
By the time we were back on the ship, it was less than an hour before new guests started arriving and the ship was bouncing again.
ETA: We had the same cabin, we didn't have to take anything out, it was great!
We went in and out once before 1:30, but we made sure there were no other passengers around when we did it.