Crab... I am not sure how strickly applied the low level military routes are applied I would err on the side of cauction with CANP. But on weekdays, it is probably best to leave North Wales to the RAF.
To add what you said about the military briefing and authorising has a place in GA, but does not always work when someone is operating outside an organistion. But you should read AAIB G-BIIJ where the clubs instructors auuthised a flight to a stag night. The difficulty here than the instructor having checked the weather authorised him. Of course I do not how the conversation went, but my concern is here that the pilot was in the mindset that if the instructor authorised him the trip was possible.
Had it been me I think I would have perhaps asked question about his gameplan it the weather became worse, such as landing at the nearest airport or turning back and hiring a car, have they got their driving licence and a credit card with them, had the pax been briefed on the possibility that they might have to make other travel arrangemnts. I think I would kindly reminded them about the consumption of alcohol and substances, bearing in mind it was a stag night. I would add that on the fatal outbound which ended at Tryfan, there were traces of drugs in both the pilot and pax, again this says alot about the attitude of the pilot in terms of his operation.
Now going back to the military, I once went on a secondment to a University Air Squadrom, at the begining of the day an Cadet Pilot would be delegated to give a full weather briefing to his instructor and fellow cadet pilots, it was from a training point a really good training exercise.
On that basis, in the civilian world it does make me wonder if we should do something similar and get our student pilots to do something similar to place more emphasis on weather planning and having an alternate gameplan when the weather is worse than expected