Socci, I'm sure she would lose interest at some point naturally - there aren't any breastfeeding 10-year-olds, despite Little Britain.
I have a friend who weaned her 2.5 year-old by explaining to her that mommy wanted to be able to have coffee and wine again.
Obviously, if you want to quit now, going away is a good opportunity. You probably could go away, not express, and still be able to feed when you get back.
You certainly should still go on the holiday, whatever's going on, as it sounds like a lovely break!