The short answer is no, there was no particular area or squadron assigned to an admiral of the ____ during the Napoleonic wars (in the way, e.g. that the current US Fifth Fleet is assigned to Bahrain, the Third Fleet to Point Loma, etc.).

The longer answer is: In the structure that was set up during the Dutch wars, a captain became an admiral only on the basis of seniority, and would progress through the ranks only in order of seniority. So there was no notion of promoting "out of grade" or anything like that. The structure imposed unfortunate limitations on the Navy, not least that men would qualify as admiral only at the end of long careers and not on the basis of merit. After 1743, the number of admirals in each rank was no longer fixed at one (that is, you could have more than one fleet admiral, though in practice there was generally only one, and more than three admirals of each squadron), and after 1747, a new rank of admiral "without distinction of squadron" was created, which would allow a man to be promoted admiral without being assigned to an active command. That was specifically understood to be a superannuated position, but it did allow for the Admiralty to reach as far down as possible in the captain's list to promote men.

The old distinction of the red, white and blue squadrons was meant originally in the 1600s to divide the fleet into its component parts: the idea being that an admiral of the red squadron wold command the main body, the white the van, the blue the rear. This was a theoretical organization, though, and did not always pertain in practice; for example at the Battle of Schooneveld the Anglo-French fleet, with the French ships forming the white squadron, Prince Rupert led with his red squadron, put the French white in the center, and let Edward Spragge's Blue squadron form the rear -- one of several examples of exceptions.