Preparation our 2 tablespoons water into small bowl; sprinkle gelatin over. Let stand until gelatin softens, about 10 minutes. Lightly spray six 3/4-cup ramekins or custard cups with nonstick spray. Heat cream, lemon peel, and sugar in medium saucepan over medium-high heat, stirring constantly until sugar dissolves. Increase heat and bring just to low boil, stirring occasionally. Add gelatin mixture; remove from heat. Stir until gelatin dissolves. Cool mixture to lukewarm, stirring often. Stir in buttermilk and vanilla; divide mixture among prepared ramekins. Refrigerate panna cotta until set, about 4 hours. DO AHEAD: Can be made 2 days ahead. Cover and keep chilled. Using small sharp knife, cut around panna cotta in each ramekin. Place plate atop each ramekin and invert, allowing panna cotta to settle onto plate. Top with berries and serve chilled.