Unfortunately the usual car park has been now blocked with boulders. I've put a comment on the BMC access database and wonder if they can contact the landowner and find out what the problem is. Usually fly-tipping.
The larger lay-by back towards Tintwistle village would be an option with a walk along the road (bit busy). But at the moment it is closed for roadworks (looks like they are fixing the wall).
Looking on the CRoW map the boulders aren't actually covered, just the quarry and apparently people have been told not to climb on the boulders before according the another comment on the BMC access website. Copied below
"Went to climb the boulders 23.06.20 told by farmer with a gun that it is private land below the track and no climbing is allowed..so the quarry seems to be okay but we were watched out to make sure we didn't climb the boulders"