Alnwick Garden

Garden staff shed their inhibitions - Northumberland GazetteThe willing recruits have been photographed throughout the attraction with carefully positioned props and plants covering their modesty.
Proceeds will be donated to The Alnwick Garden Trust, which seeks to change the cultural environment for the better and help people transform their conceptions, expectations and aspirations and those of their communities.
The calendar has been shot by Garden volunteer Margaret Whittaker and will be available to buy from the attraction’s gift shop for £4.99.

There's a second article from the Northumberland Gazette, but even the garden's official page does not mention mail orders.