Let me say first and foremost that we (Dad/Sandy, Chris/I) are very excited about this upcoming trip to England, Ireland, Scotland, France and Wales!
This trip is partly a cruise (Princess) and then an extra week traveling by train. We planned and booked the extra week ourselves, but we did use an agent to book the cruise portion. Neither was as easy or cheap as we initially thought. In the process, the four of us have navigated new technology, flight and cruise itinerary changes, creeping budgets, and general planning problems—and honestly not always with the best of attitudes—yet we hope we have prevailed.
Anticipating a UK summmer (aka often cold and rainy) was just the start of this new adventure; it's really hard to pack appriopriately. Do you bring sweaters, rain boots and jeans—or short, tanks and flip flops? If you bring a full supply of both, your luggage becomes unmanagable. I packed a little of both, but mostly lots of layers!
In case any of you are wondering... another packing quandry: What happens if our luggage is delayed or misdirected en route to the embarking port (Southampton)? If this happens on our domestic flights (to Boston), the suitcases will just be returned to our homes, and so we will be wearing Princess sweats the entire 21 days! If it occurs during the international flight (Boston to London), the cruise line will bring it to our next available port (because we booked our international flights through Princess). So our solution is this: We packed one large suitcase (to be checked baggage) that has our formal clothes and half of our day clothes. Then we also packed a carry-on suitcase with the other half of our clothes, so we'll have kept at least some of our basic clothing options on hand. Also, this lets us better manage vital supplies of medications and other absolute necessities. (Case in point: Just days before leaving, I came down with a bladder infection and had to visit urgent care for antibiotics. I should be finished them by the time I board the ship—unless it worsens for some reason. Its always something!)
Another travel consideration is that our domestic and international flights simply do not connect well. The layover time after arriving in Boston from home is just too short to risk missing our flight to England (and coming back to Boston from London, the layover is overnight). So we have a night's stay in Boston on either end of the trip. And since our flight to London is an early evening departure from Boston, that basically gives us a whole day to explore Boston before we board—a bonus tour day!