They definitely visit adult-only tables - at least they have every time we've done a character meal, and we're adults only.
I don't know if letting the host/hostess and your server know you don't want them to come over would do any good. The seating is in a big room, so you'll be seeing them anyway, even if they don't come over to your table itself, they'll be right next to and around it visiting the other tables, especially since those people booked a character breakfast to see the characters.
If it's going to be a huge issue for you, you might be better off finding out where and when Pooh will be in the parks (I've encountered him in Great Britain in EPCOT) and letting your husband meet him there. Just a thought.
(That said, when my family and I did Crystal Palace a few years ago, Pooh was centrally located near the buffet line and the other characters are who came around. But yes, they visited every table.)