@Peach026 -- I'm sorry for your frustration. That's disappointing. :-( We also just got our quote for the add-on, and it was astronomical ($$$). We booked it on our own and are saving a couple thousand dollars for the same hotel and number of days. It almost seems like they don't want to be bothered coordinating this add-on for ABD folks.
I do have a question (@ anyone) for the ABD trip itself. We are arriving a day early (early morning), so we'll have nearly two full days on our own in London before the welcome dinner. We're trying to take it easy on arrival day in case we aren't able to sleep on the plane, so we're planning The British Museum and a show on the West End in the evening. For the second day, we were thinking of taking a Westminster Abbey / Parliament / Downing Street / Whitehall / Buckingham Palace walking tour (with entrance to Westminster Abbey). I know we'll be seeing some of this on ABD Day 2, but is the overlap minimal enough that this tour would be worth it? We also considered doing the Warner Bros./Harry Potter excursion, but that's a full day, and our 10 year old is not as big of a fan as we are (despite our attempts to make her one!)
Any recommendations?