Washing a wool mattress topper?

[Cantonet]

Can I?
It's a m&s mattress topper with wool fleece one side & cotton quilting the other. It says it can't be dry cleaned or anything other than spot cleaned on the label.

What is the filling?

We wash our wool duvet in the washing machine and the pillows (or down the launderette if I can be bothered)

I have one that sounds similar - lambswool with a cotton backing. I've never bothered to wash it but I put it out to air on the washing line occasionally. If I thought it needed washing I'd put it in the machine on a wool wash cycle using pure soap (not detergent).