I would NOT use Lt.Bob's (40-civ) or Solver's (50-civ) patches, as both are seriously flawed. Both LtBob's and Solvers patches have bugs that prevent the AI from using it's bombers if you have a single fighter in the air on Intercept. Neither has fixed or updated their patches since the bug was revealed some time ago.
You are more then welcome to try the Wolfshanze Mod, which allows for 40-civs and has no bug as the other patches do with bombers. The link is below in the sig-line... if you don't want the full Wolfshanze Mod, the game patch for 40-civs is also offered as a separate download.