Well, I could offer two SPmissions in mini-campaign mode, but they are in german.
It's quite realistic
but I guess it would be a bit too confusing for you.
One is about a secret mission to find and sink an early war RN sub hunter group.
BdU gives you updates and your crew interacts verbaly.
The other one let you take a guest aboard who takes over the command of your sub and lets you do some weapon testing near wilhelmshaven.
TheAvonLady gave me some support to translate a wolfpack attack mission for SP into english, it's no "mini-campaign style" but an instant action mission.
It was scripted when patch 2 was state of the art.
If someone would be so smart and transform the two first missions into mood-matching english (this navy/sailor babble you know) I'd try to rewrite the messages in my bad english first to show the transformer what the stories are about.
Your turn!