Yep and I'm sure that the 1SL or whoever is in charge of boats has been told - we cannot retake the FI, ensure you do not lose them.
Don't forget there is a few more troops on the islands than before - all they have to do down there is drink, train, drink, exercise, etc - if push came to shove I would put a fair chunk on any invasion force given a really bloody nose - typhoon or no.....
And yep, any T boat "down that way" or on long patrol will have a set of charts for going south to be noticably not there.
Subs are the best offense/defense weopon to degrade land/sea targets.
Unless the captain "parks" the sub on a scottish sandbar they do not get easily spotted.
if you can't find it you can't hit it.