I managed to make it into Reykjavik harbour in October '40 on my one and only harbour raid ever. Something I normaly never bother with, and won't again. Even then it was hard enough, five destroyers guarding the port. Depth was about 40-something metres further out going down to 1 mtere under the keel at periscope depth at the harbour entrance. A dido class, an auxilury cruiser, a large cargo. In the period you mention, I wouldn't even dare try. But, 'do you feel lucky punk'.
Auxilury cruiser, Reykjavik.
http://img243.imageshack.us/img243/791/auxiluryreykjavikzz5.png