Preheat oven to 425F. Blend the oats, flours, baking soda and salt in a blender (or bowl, by hand). Add the butter and use a dough setting on the blender, or a fork or pastry cutter to incorporate into flour. Place in a bowl, then stir in zest and chocolate chips. Mix egg and milk, then pour into dry ingredients and stir until evenly mixed – don’t over-blend! Drop with a spoon onto a baking sheet (leave lots of space, see below!), then mix the lemon glaze ingredients separately in a small bowl and brush on to the tops of the unbaked scones. Bake for 12-15 minutes.