But wasn't RN naval doctrine focused more on BB than CV, CVs in RN were only intended for support role, not capital ships like USN.
Everyone's doctrine was focused on battleships. British construction reflected the battleship threat from the European powers, Germany and Italy, who had no carriers worth speaking of OTL. AIUI, one reason that the USN built so many carriers was because they had relatively few in the late 1930s and wanted to have a 1:1 balance between battleships and carriers, hence the plans of the Two-Ocean Act, which, as you point out, wouldn't have happened ITTL, although some sort of One-Ocean Act probably would have, in response to Japanese construction.