The military would disagree with you for a start
Disagree with what?
That they fly anywhere anytime anyway?
Many years ago, long before I started flying, the RAF was bigger than it is today, and did a lot more flying. There was no ais.org.uk back then, so how did pilots (those that go places and didn't spend their days hanging around flying schools/clubs) find out this vital information without which they would surely collide with an RAF aircraft?
They didn't, and it didn't matter.
The sky is big, the RAF navigates for most part visually (they really are tremendously traditional in this respect, which is why I wonder what capability the RAF would have if they ever had to do something
big for real, but that's another matter) and they look after themselves. They get a lot more of a radar service than PPLs do. The front line jets also have radar.
But today's RAF could not muster enough planes on a given day to create a statistically significant collision risk. You are far more likely to hit a parachute with a lawn mower attached to it
If you can get a radar service, ask for it. They might give you an FIS only but (assuming you have a transponder, mode C, which is a
big assumption) they will separate other traffic from you.
If you fly through an AIAA then obviously call them up.
The NAVW notams are IMV worthless. It's somebody covering their ar*e.