That's good news.
It certainly is, and a nice surprise.
Happily the shimano/campag cassette arrived today and I appear to have managed to fit it (I say appear to, until the bike is on and everything is working I won't quite believe it's ok). It will surprise no one to learn that it certainly did not all slide on in one smooth go as demonstrated in the link posted upthread, but I still managed to get it on.
It didn't need the spacer that came with the Kickr Core, despite some stuff online saying that you did need it for 10-speed cassettes. I did try but there wasn't room for the smallest cog, so took it out again.
Later on I will persuade the half of the marriage who doesn't mind the massive spiders in the bike store to get the intended bike out for me for a proper test.