Help !

This is quite common and should clear up by itself but feel free to remove some along the way if you don't want it in the tank ... pretty sure it's harmless though

Yes, I had that with the first of my two pieces of wood - I gave it a scrub during every water change regime with an unused toothbrush bought specifically for fishtank cleaning purposes but it eventually disappeared of its own accord after 6-8 weeks. With the second piece of wood, I kept it in a bucket of boiling water which I kept topping up with more boiling water for the first day or two, and didn't have any white fluffy stuff on it.

Doing a water change today so I'll try and get most of it off :-) and my carpeting plant is actually growing !!! Not had much luck with carpeting plants before :-)