Choosing a modern Royal Navy ship for the Second World War

Which currently commissioned Royal Navy ship would you take back to the Second World War?

An Astute submarine is preferred for its imagined ability to detect wartime U-boats and direct anti-submarine operations, with a Type 45 considered for its radar and surveillance capabilities.

The question is initially understood as choosing a wartime command, prompting a choice between Renown and Eagle. The Eagle proposal includes repairing her fuel lines and carrying extra Swordfish for an imagined Taranto strike of 48 aircraft, divided equally between Eagle and Illustrious. Once the panel clarifies that a currently commissioned ship would travel back, an Astute submarine becomes the preferred choice. Its modern sonar is expected to exploit the greater noise of wartime U-boats and help direct hunter-killer groups. Locating submarines across the North Atlantic from a harbour remains conjectural within the time-travel premise. A ballistic-missile submarine is rejected because of the imagined risk that Churchill would order its nuclear weapons used, while an Astute could bring Tomahawks. A Type 45's radar and surveillance capabilities are considered less strategically useful than defeating the U-boat threat. The imagined submarine deployment also includes torpedo attacks on German capital ships during the Norwegian campaign.