Yep, delay her for a year or if you do not want to do that, go in the middle of the year when the weather is nicer in Europe
My SIL goes pretty much every year for at least 6wks (over there now), her DD is in Prep this year and her older DD is in Grade 3, if your DD is confident and picking up work pretty quickly, she will not miss much in prep.
SIL does some work with her while on holidays, just basics like Golden Words and basic reading and writing and maths to keep her up to speed.
As Sopdet has mentioned, it's pretty educational as well for them to be OS, if she was home schooled, it would be part of the curriculum