Re Balmoral, we visited there a few years ago - not in conjunction with a cruise - and it was wonderful. If I remember correctly, the Royal Family doesn't arrive til perhaps late July/early August. A private tour isn't necessary - just the transportation part. You just show up, pay your money (seem to remember that it's modest) and walk around. Only one room - a ballroom - in the house is open to the public. They've pulled some pieces from various parts of the house. But it's the grounds that are spectacular: the gardens, the Fell ponies. We were really glad we had the opportunity. Enjoy your holiday.