A good source for you to start would be "Iron Coffins". That book is either a fictional historical account or a historical fictional account depending on your opinions.

In any case, that book has some good descriptions that would probably fit your bill.

When describing an attack by a U-boat, it is important to know that there were two different attacks. One is a surface attack and the other is a submerged attack. Different things happen for each attack with different crew doing different duties.

As for it being a calm operation, I would agree, especially for a submerged attack. While there might be some excitement in getting to their action stations, once there, the attack is a professional operation. I would not imagine much shouting and there would be little/no chatter. While I never served on submarines, I have been in combat situations and during combat, people are quiet and focused.