That is a DAUNTING task.
You're basically going to write one book trying to cover 1/4 of the military aircraft on the planet
at the time of CS!
I'd say go 'episodic' with the whole project:
Episode 1 - The Royal Air Force: " Undaunted by Odds"
Episode 2 - The Fleet Air Arm: "Down to the Sea"
Episode 3 - The Colonials: "Guardians of Empire"
Episode 4 - The Territorials: "A Well-Ordered Militia"
Episode 1 would cover only the actual R.A.F. and its ground facilities located on the Home Islands or Crown Colonies.
It would not involve any 'cousin services' in the Empire, nor any militia units.
Episode 2 would cover the Fleet Air Arm of the Royal Navy, its ships, and its aircraft.
This would include any long-range flying boats owned by the Navy.
Episode 3 would cover the Air Forces of Ontario, Newfoundland, Australia and New Zealand, South Africa, India and the largest of the various British Overseas Territories (Bahamas, Bermuda, Gibraltar and Falklands).
Episode 4, if necessary, could cover any specific militia units that you wished to create not under direct government control. These would include not only places under the dominion of the British Empire, but those 1.) in hotspots like Hawai'i and 2.) allied nations like the Confederacy and White Russia.