When in your career is this? do you have radar so you can detect the attacking surface craft? if so stay out of visual range and watch his patrol pattern, you may be able to find a suitable gap in which to get in and deploy the agent.
I think that your radar should also give you locations for shore batteries. I would strongly suggest attempting the mission at night,
It helps to be at a complete stop before you deploy the agent as for some reason his rubber raft scraps along your boat and sounds like the rusty gates of hell being opened. You do need to be surfaced for the launch of the raft.
Go in slow and if possible semi-submerged to reduce any visual profile.
good luck
