Welcome aboard.
Whilst I admire your commitment to just jump straight in at 100%, as you have discovered there is a steep learning curve.
Might I suggest playing some single missions at less than 100% first to get a good feel for the game?
As Snestorm has suggested, maybe start with map contacts and WE Assist on at first.
Then you can put all your concentration into getting into a good attack position, and evasion procedures after the attack.
Once you are comfortable with this, then maybe turn off the WE assist, so you have to calculate your own torpedo solution.
Finally turning map contacts off as the last step.
Just a suggestion mate
When I started out I found 'The Hunt' to be a very useful link.
http://www.subsim.com/radioroom/showthread.php?t=88961
Good Hunting Kaleun