I dare not tell W if/when we are away for a couple of nights because she will be back in the house and going through my things etc.

In a few days she's going to receive a childcare offer from my L for the kids to live most of the time with me.

W says she wants a calm life.

So how about "Hi, kids are very happy, settled and it's always very calm at home. Nothing booked at the moment." ?