Get there days ( I dont mean 2 days before the fireworks start I mean a good 4 days prior so you can get into a perfect position, stay away from the mines, keep it slow and low (deep in this case) so no one finds you. Perferably with engines at all stop and sitting on the bottom, only surface for air.

DO NOT stay surfaced for long or the RAF or a group of distroyers WILL kill you, no matter what you do if they find you, you are dead.
Stay silent lay deep is the main thing I can tell you. As I said, lay on the bottom. silent running.
Look at the campagine files for further details.