1. For civilian a/c, it's not mandatory to get clearance to enter a MATZ at any time other than those which are encompassed by other controlled or restricted airspace, in which case they are considered to operate under the rules of that particular class of airspace.
2. At weekends, many military airfields host gliding activity. Despite having the protection of the ATZ, many will say that they operate to a rad of 3nm up to 3000ft and if you make a call on the frequency they will tell you to remain clear by this margin.
Typical nonsense and hypocrisy from the Queens subsidised flying club, although you should remain outside the ATZ there's nothing to stop you transiting 2nm and 1ft from the airfield without calling - just like the military do Mon - Fri with every civillian ATZ.
Of course good airmanship dictates that you make the appropriate calls and keep a good look out, but MATZ airspace (unless within controlled airspace) is the open FIR and it's incumbent upon the military pilots, no matter what they are flying, to keep to the same rules as you.