Thank you for your question! Clamming is a very popular activity here on Prince Edward Island.
One of the best locations for clam digging on the north shore is the New London Bay and it is only a short drive from Cavendish.
Be sure to pick up an area tide chart at the Cavendish visitor centre so that you can check it for low tide times before you head out. I find going out an hour before low tide is a great idea. I'd also keep an eye out for any yellow signs warning not to clam in that section - just in case.
Another tip is to soak your calms in some salt water for a few hours afterwards to get rid of some of the grit.
Good luck with everything and have a happy clamming good time!