The letter M**** used by UK aircraft refers only to military aircraft. When I was in the RAF (many moons ago) each aircraft had a Mike radio callsign allocated.
For example, it worked like this - MOGKG translated as follows:
M: British military aeroplane.
O: Command (eg Transport Command).
G: Aircraft Type.
K: Squadron.
G: Individual aircraft.
Before my time, the radio callsign was painted on the nose cone of transport aircraft.
Other countries use a similar system for their military aircraft. I seem to remember that Holland uses PE (eg PE-XAD) and Belgium OT (eg OT-CBG).
So, you are going to have to join up and then wait a very long time before you get to MIKEY!