Go to
http://www.34thflotilla.com/MultiMissions/ and download the AirRaid.mis file. It is multi-player, but you can put it in your SingleMissions folder and play it single-player if you want.
The mission starts slowly... just a few planes, but it gets more and more instense as the mission proceeds. There are a couple of Elco patrol boats too, but you can take them out with the Flak if you have a decent one. I'd suggest taking a U-Boat with plenty of Flak.
Hope that helps...