Hi guys,
If attempting the English Channel, or any Coastal area near the English coast, I strongly recommend submerging for the day light hours and only attempting passage during the night.
Also remember that once spotted the Air response will be actively looking for you and will be for many hours. I would recommend in these instances submerging for at least 6+ hours.
You may find this thread interesting as well
NYGM 2.2 Escort Logic Question <== link
Hope you make it out alive and wiser 