Using a Franco-Spanish fleet to secure the western Mediterranean

How should a forty-ship Franco-Spanish fleet secure the western Mediterranean and respond to the Royal Navy?

Blockade and besiege Gibraltar, remain at sea, and accept that a Royal Navy attack is a matter of when rather than if.

Gibraltar is the geographic key because it controls entry to the western Mediterranean. A combined blockade and siege would put the fleet where it can support the land operation and contest British access. Remaining concentrated at sea also gives the Franco-Spanish commander a better chance when the expected Royal Navy attack arrives. The plan cannot avoid battle, but it can choose a strategic position that makes battle serve the campaign.