We had CCF at school, which was taken pretty seriously. Granted we had a number of pupils whose parents were army, or were working in the defence industry.
Pupils did go on to join the army, but on the whole, considering the number who were army brats, I don't think a notable number, perhaps a couple a year?
It wasn't about glorifying war, I would say that if anything it was about the horror of war, but acknowledging that sometimes it is necessary. They were open that war mean casualties, losing friends, whether that was doing first aid or planning an "exercise", it was something that was talked about openly.
It was about team work, problem solving, and being aware that what we were doing was very much playing at being soldiers without the risk. Anyone in any doubt, who didn't take it seriously, would have felt the full wrath of the Colonel, and he was probably the main teacher that could have the whole school, plus the younger teachers quivering if he was angry!
However I don't think Invictus has any place in school more than any other charity who is trying to raise awareness. It certainly shouldn't be being included as part of the curriculum, and it's rather grandiose for H to think it should be.
And if war is coming, then telling them "don't worry, if you're injured then you can play in the Invictus games" is not really going to bring any comfort to children who are faced with war - it's just so far removed from their everyday life it's like saying they might live on the moon when they're older.
If you are wanting the pupils of today to hate war and work against it, then real soldiers, who have been injured and have a story to tell, would be much more impactful.