Fire Cat
I believe that there is no legal requirement to have any fire cover at all, even for public transport.
The ICAO annex specifically uses the word "recomended" and the MATS part 1 states that "to comply with the ICAO recomendations".
Although I have not read them recently, so I could crash and burn.
The authority to land at an aerodrome rests with the aerodrome operating authority.
Once you write the requirement into your ops manual it becomes law as your approval is to operate in accordance with your operations manual.
It is entirely possible to land legally under an AOC with no authorised fire cat, I have done the trials.
But my advice if asked, would be to comply with the ICAO recomendations.
Stay safe,
MM