Ok - from a controller's pov;
The difference is not between non-precision and precision approaches, but between procedural & radar approaches.
The scenarios you are talking about are procedural approaches (which you are often practicing in a radar environment).
If you are cleared for an approach, you are cleared for the whole thing, descent included.
Now, here's what you see as an inconsistency: You are a training flight. You want to practice a procedural approach, but the airfield has radar, and the commercial traffic is making radar-vectored ILS approaches. You're ready for the approach and nearing the beacon however there's ILS traffic coming down. Now I cannot clear you for the approach because I would lose vertical separation, so would you like to spend more money going around the hold again please? No? Ok, what I
can do is clear you outbound with a height restriction until I can see you are clear of the radar traffic. So you get "cleared for the xxx approach rwy 0y, maintain altitude 3000' until advised".
Does it make sense now? We know time is money for you, and this is the
expedition part of our mantra, "safe, orderly & expeditious".
Regarding mil/civ phraeseology; there are a lot of differences, although these are becoming less as a move is made to consolidate the two styles of ATC. What you have to remember, though, is that all Britmil pilots are trained to the same standard and the same goes for Britmil ATCOs, the idea being that at any base, even on deployment or in open warefare the baseline remains the same & instantly recogniseable. "Quaint" ideosyncracies like "cockpit checks, report complete" stem from the chance that the a/c you're vectoring could be a badly shot-up single-seat FJ with a badly-wounded pilot. The mil ATC method takes a lot of the pressure off the pilot and the way the phraseology is aranged acts as "attention-getter".
Hope that's helped, however I would always advise
get into the tower!. Controllers may seem fierce & unapproacheable Gods (goes without saying, that last bit!
but feed them enough chocolate biscuits & they are pussy-cats & eager to help!
ap