hotel magnum:
finally got some at Dorchester post office Dorset lots in the rack on the wall, the lady did not know if I can get it stamped by any PO or I needed to go back to dorch.
I’d expect that any main post office could stamp it, maybe not your little local PO in the corner of the local shop.
But I’d try my little local one first anyway if I was you. That wouldn’t take long and might save you trailing all the way back into Dorch.