RN attack subs are equipped with Tomahawk cruise missiles. Not enough to do major damage, but they could be used in a Doolittle style raid against a couple/few targets (like powerplants) that would send a message.
That all they could do, send a message. They could play defense and stop resupply to the island.
But they have no ability left to project power and force their will. The fleet and airpower they used in the Falklands war was enormous compared to what they have left today.
There are four fighters based on the islands, that’s it. And no hope of delivering others. Say some morning a commando team landed blows up the 4 fighters. Capture or disable that airport by any method, and there is a company of British infantry to deal with and that’s it.
War over. The Brits could not deal with it without dragging NATO (read USA) into it.
Its fun to have nostalgia for the days of British military prowess, but now they are a hollow force, a mere shell of the past.
The UK only has a small amount of Tomahawks (less than 100). The mainstay of UK missile strikes is the Storm Shadow, the Anglo-Italian-French missile, we have 900 of those.
Admittedly For the RAF, but they can easily be used by the RN, as they are built to be adaptable to air or sea.