Last summer I cycled from Yarmouth up to a folk music festival in Canso at the northeastern tip of mainland Nova Scotia. I rode up the Annapolis Valley on the Bay of Fundy side, across the Rawdon Hills to Musquodoboit Harbour just above Halifax, and up the Atlantic coast to Canso. The coastal cycling up from Musquodoboit Harbor was great with only light traffic in late June. I drove the section from Queensport to Guysborough in a rental car to get back to Yarmouth after the festival............wish I had been cycling it!
I stayed at good simple campgrounds at Musquodoboit Harbour, Sheet Harbour and Sherbrooke. The one in Sherbrooke is at a convenient, in town location. Carry some food between Sheet Harbour and Sherbrooke. You won't find many stores on this stretch.
There is a particularly scenic campground 10K beyond Canso at Fox Island, with great tent sites right on the water of Chedabucto Bay.(Sea Breeze Campground) Should you arrive in Canso during the July 4th weekend you'll find accomodations full everywhere due to the annual Stan Rogers Folk festival.
Warning: Shoulders are rare on the roads of Nova Scotia. Cycling can be treacherous when you get into traffic. The back roads are rough and pot holed.