I seem to recall seeing it at Bramble House, on the West island:
You can call and see if they have it. They have an outstanding British Isle toffee selection.
Love that stuff. I love putting it in the freezer and smashing it into bite size pieces.
They also have a brand, Thornton's, which is also outstanding. I have also seen Thornton's in the past at Festin du Babette, but again, I would before to make sure they have it.