Ah, I think you're right, sorry.
I'd been going off what I remembered from the recent public meeting, rather than having another look at the plans. It's the school that has land reserved for future, but isn't actually being built, whereas the P&R does look to be being built.
I'll be slightly disappointed if it is the 33 that serves there - I'd been led to believe that the 33 was going to go round Shawfair station once the new access road from the Millerhill bypass to the station was built (which is probably soon, given that the signs for it are now erected but taped over). If it's also extended to the new P&R and therefore only serves the Station in one of the two directions, it'll not be as good of a link to the station.