This. Exactly this.
Let's assume that it is spring 1941 and all four German battleships (SH, GN, BM, TP) and one carrier (GZ which is in this waht if at least on par with its counterparts of the Royal Navy) have formed a battlegroup and are already in the North Atlantic looking for convoys.
The Royal Navy has four options:
A. Seek and defeat the German battlegroup in the Atlantic. This would require to establish their own battlegroup(s) that can outfight the German ships, combined with many screens and aircraft. One battlegroup would contain at least two carriers and six battleships to ensure superiority.
B. Defeat the German battlegroup on its way home to port. Either they go for Brest or they return to the North Sea. Pick one. RAF support is possible in both cases, Brest is more convenient.
C. Wait until the German battlegroup has returned to port and damage/sink it there. If they would be foolish enough to go to Brest (or any other port on côte atlantique), the RAF would be glad to make the port #1 priority and the RN would send carriers to strike. The mooring German battlegroup would be a sitting duck for aircraft, even more so after the ships got damaged in a previous attack.
D. Once in Brest, they could prevent the German battlegroup from leaving the port. Mined exits, Royal Navy waiting in the Bay of Biscay or close to it, and RAF on alert.
Why would the Royal Navy pick option A. or B. and risk her ships in open battle if they could wait until the German battlegroup returns to port and bomb it there? The German ships would savage one or two convoys - let's say they sink 50 merchants - before they would have to return home. Supply ships and refueling en route would not change that.
How would the Germans counter option C? Would they build giant bunkers for their battleships and their carrier? Those bunkers would be huge and would dwarf the already sizeable sub pens. However, those bunkers would prolong the lifetime of the German ships until they get damaged and sunk one after the other in the Atlantic or until the US joins in with strength. So, maybe battleship raids until 1943? Maybe two raids a year? If they are lucky.
Still not worth the effort. Uboats would still be much cheaper. The whole German battleship and carrier surface raider armament is waste of ressources.
Why not occupy and establish Iceland as a sort of unsinkable aircraft carrier and submarine base in 1940? Send oilers and transports with troops, flak, aircraft, building equipment, ammunition and supplies. Build airfields.
Later in war, oil, avgas and supplies could be brought in continuously by milk cow submarines. Aircraft would prevent the presence of the Royal Navy, long range air attacks from the British islands would not be likely before 1943, submarines could refuel there and German aircraft could screen the seas or hunt down Allied aircraft. Maybe Bismarck could have saved herself to Island?