Otherwise, all of the big coffee shop chains (Costa, etc) sell ground coffee, etc, to take home, so it might be worth asking whether they also sell the sprinkles to go with it.
Not a lot of help with the OP I know, but, a moan:
Nescafe cafe menu coffee sachets used to contain a tube of their chocco topping when they first launched, then after a bit I realised they'd quietly stopped putting it in as part of the deal :-(