Currently it should be blocking unpausing until step 7 or so... and it also should auto-pause once the ship reaches step 8(?). I did both of these things for the reason you're saying, but maybe I need to do it even more "locked down", at least for the Basic Tutorial.
Something that helped me a lot was exploring how the firing solution changed when I changed various parameters in the TDC. I don't know if there's a way to build that kind of exploration into the tutorial. Maybe by splitting it up into segments, asking the user to handle only one measurement at a time, and illustrating how the firing solution changes?
It is, however, annoying to start up the tutorial and click next-next-next-next to dismiss all the text when playing around with its scenario. Maybe a "dismiss tutorial text" button somewhere in the start of the tutorial?
My first attempt at the second mission I had the periscope up too much and forgot to dive so the escort vessel rammed me. Maybe tell the player to pay attention to the detection-o-meter?
Second time I was very careful and managed to get hits with four torpedoes on the first salvo. I had to bring up the scope to watch. I had no expectation of even getting close so it was INCREDIBLY satisfying. Then at first it seemed like I'd escape but I lost track of the escort and then got blown up by depth charges.
I'm absolutel going to try again, though. This was a lot of fun.