I manage to get to the top of the Peak District a few times a year, but to force my lazybones daughter onto a moor to look at a dimple on a stone would cost me an arm and a leg in bribes !

Probably the ones in the British Museum.

Greenwell's Harbottle Peels thing (but it's not actually got any cups on it) is meant to be there, as is one of the Cist covers from Dod Moor. I dunno if they're on display though.
Dunno if there's more in the BM, but I suspect there will be.

Nearest RA to Kent still out in the field probably is either the ones in the Peaks, or the Fyfield thing Juamei was asking about the other day.