I doubt there will be many kids aboard. WE sailed Royal Carib Med a few years ago in late Sept. and the few kids on board were mostly little and not in school yet. My daughter was 10 then and still had a great time since she's well traveled and was excited about being in Europe for the first time. I suggest trying to do a little research/immersion ahead of time with the kids (books, on line, etc) about ancient Rome, etc -- or wherever you're calling. You can read the article my daughter and I wrote about our cruise on the main page here of the family section -- it's called Cruising Europe with Kids.
Smooth sailing,
Luisa Frey Gaynor
Family Cruise Editor