I will ask about about PGL (we went together a couple of years ago and had a lovely time), but I really don't want to send him away for a week if he'll hate it. It's a tricky age.
I will take some days off here and there, but I am saving my leave for winter when we're taking a longer trip abroad. There are times when I've thought about cancelling that trip so I can take more time off over the summer, but that would make me quite sad.
His brother lives in student digs. It would damage their relationship to send DS2 to him, but they are going away together for a week which will work well. Neutral grounds.
I'll look into the moped thing, and GAME comps (I don't know anything about this, so thanks for the heads up).
Paying him to read doesn't sit well with me. I want him to read for the pleasure, not to earn money.
The fitness challenge is a good one, and something I was thinking about.
He has a (sort of) home gym (just some dumb bells, a mat, and a punch bag) which is good when he's motivated.
We had a walk at lunch time and he's going to look to see if any of the local football camps need helpers. And surprisingly he said he'd attend a specific football camp if he can go with a friend.