Strictly Dianne is far different from the Dianne in Joe's vlog. She is all professional when it comes to mainstream TV, knows how to conduct herself and is quite composed. She was that way on Sunday brunch and from previous interviews I've seen. She is not going to act as a cringey teen for filming Strictly.
Also don't think she will vlog much of it either, it seems like she didn't vlog the pro tour, so maybe she won't with Strictly, but those dancers love the camera, they are all performers after all, so having a camera in their face doesn't phase them at all.