I have played a campaign from Bergen and decided to take a few patrols in the Arctic. It was very quiet, but there were some convoys now and then. I wrote detailed war diaries about the patrols in:
http://www.subsim.com/radioroom/showthread.php?t=151090
I can't pinpoint you to the right posts, but if you check my war diaries that I wrote while sailing in U-552 as commander Alfons Dietzmann, patrols 1 - 4 you'll get a picture of what it was like in the Arctic 1942 - 1943. The posts are written somewhere around may - june 2011.
There is one good thing about the Arctic convoys - minimal enemy air activity

Beware of carrier borne aircraft though