Where could Bismarck return without French ports?

Where would Bismarck and other German raiders go after a sortie if France denied them Atlantic ports?

They would have to return toward Germany or Norway through the northern passages, where a concentrated Home Fleet could wait for them.

Bismarck, Scharnhorst, and Gneisenau would have to return through the same northern exits they used to break into the Atlantic. They could no longer end a raid at Brest or another captured French port. That predictable return route lets the Royal Navy concentrate capital ships at Scapa Flow instead of guarding several possible destinations. A raider that survives the outbound passage must therefore run the concentrated barrier again while potentially damaged or short of fuel.