If you are interested in the "military" side, like running around in flak jackets when it's 30 degrees, fine. If you are primarily interested in ATC then I would recommend NATS.
HD is absolutely spot on! In the services you are an Officer/SNCO/boat driver first and controller second and there will be many occasions/posting when you will have nothing to do with ATC.
If it is the service life that appeals then go for it (you will experience things that you just can't get in civie street (down the lakes at 250ft 480 kts
...being mortared
))
If it's ATC that appeals.....go civil controller.
Fred