Preheat the oven to 350 degrees . Grease a 9-by-13-inch baking dish. In a large bowl, combine the peaches, brown sugar, tapioca, cinnamon and lemon juice. Let rest; toss occasionally.
In another large bowl, whisk together the flour, 3 1/2 tablespoons granulated sugar, baking powder and salt. Using your fingers, blend in the butter until the mixture resembles coarse crumbs. Stir in the blueberries, then 1/2 cup cream; combine until the dough just comes together. Turn out onto a floured work surface and pat into a 1-inch-thick round. Cut into 8 wedges.
Pour the peach mixture into the baking dish. Arrange the wedges on top; brush with the remaining 2 tablespoons cream and sprinkle with the remaining 2 teaspoons granulated sugar. Bake until the scones are golden, about 1 hour. Let cool for 10 minutes before serving.