were you married to your ex, or did she make any mortgage payments towards your house? if so, then she can likely have a right to some equity.
i came across this info about CMS and property:
We’ll now include the following type of income in child maintenance calculations:
-assets such as coins, gold and property (not including the paying parent’s home)
-income generated from an asset over time such as property or land, or income generated from a sale
-any unearned income, such as inheritance, rental income and interest on bank accounts
-The paying parent will not have to sell their home or the property where they do their business to pay any additional child maintenance.
My opinion on that sentence is anything they consider to be an investment (I'm surprised they didn't mention shares) or a way of storing value other than bank accounts. I suspect it's deliberately vague so they can assess on a case by case basis, for instance, I'm guessing that a car wouldn't be included normally, but if you purchase a classic Ferrari, then it may well be included.
sounds like they mean they won't touch your home whether you sell and buy a new house to live in. but if you have a 2nd home, or some buy to let properties etc, then they could target those if they wanted to.