Soldato
not really, for one any carrier in operation would have type45 with it and running awacs cover, that pretty much eliminates any problems from surface / airborne threats..
then i'm sure we would have a sub assigned also to battle group (astute ?), and no possible enemy in the world today is gonna sneak a sub up into range very easily
most possible enemy forces are running aged diesels at very best, let alone proper blue water sub fleets with the latest tech
the above all makes threats to our carriers quite low... look at how many operations US carriers have been in in modern times, none have been hit by anything.
even old subs could give modern day ships a battering with a decent enough crew and the right window of opportunity.
Russias rearming, theres a possible enemy force with new tech subs...... the merlins wont stand a chance of finding them if there half as good as ours.