Hi Kelly, I don't know of anywhere that you can meet Lumpy and Roo. While there are many characters to meet-and-greet, Lumpy and Roo aren't ones I have seen around. Check out
www.wdwautographs.com. This site compiles characters and the places you can meet them.
If there is a particular character you want to meet, check at guest services when you enter a park. A cast member will be able to tell you if that particular character will be available on that day.
Other Winnie the Pooh favorites Tigger, Eeyore, Piglet, and that silly old bear himself, Pooh, can be seen daily at the Crystal Palace. You can get dining reservations for either breakfast, lunch, or dinner at this Character Buffet. (all characters are subject to change.)
Have fun meeting the characters and getting autographs!