This is actually a popular question, so I have a few pages that can help you here.
In short though, you can freeze lasagna before or after cooking it - it's entirely up to you. I prefer to cook it before, then let it cool... as this means it holds its shape really well when freezing.
Then just defrost your lasagna at room temperate (maybe during the day or evening), before popping it in the oven to either cook (20 mins) or warm through (slightly less).
