How about this....two men flying from USA to London for a long weekend before going to Southampton for the crossing (18 October) back to the USA. Since we're flying into LHR and taking the Tube to our hotel, plus taking the train from London - Southampton, plus going from Red Hook back to Newark Airport where our car will be, we just want to have carry on luggage (plus backpacks). We will each have dark suits, sports jackets, and acceptable shoes/shirts, etc.
We've never done this before. Do you think it all can be done with just carryon luggage?