First, let me say that I am very interested in your build of this model of the Bismarck, and I will give you any support I can (if you want). I built this model myself a few years ago, and regrettably there is no build log with a lot of pictures.
I finished the hull with putty, sanding, putty, sanding......when I thought it was even enough, I treated it with a polishing disc. The next step was a coat of parquet lacquer which becomes very hard. Then again polishing, afterwards primer, and again polishing....then the hull was ready to be painted.
I you want, I take a few pictures (spontaneously through the acrylic glass of the display case.)