Put the flour and oatmeal into a bowl and add the salt, baking powder, Xantham gum and sugar.
Rub the margarine or spread into the flour mixture until it resembles breadcrumbs.
Add the yogurt and mix gently with a spatula until it forms a soft dough. Add more flour or yoghurt if needed.
Mix in the raisins and lemon zest, then make a ball shape. Rest it in the fridge (wrapped in clingfilm) for about an hour.
Preheat the oven to 180°C.
Roll the dough out between two sheets of parchment paper to 3cm thickness, then stamp out round shapes, using a round cutter or a small cup.
Place the scones on a baking tray lined with baking paper.
Bake for about 20 minutes until golden.
Move the scones to a wire-rack, then serve warm or at room temperature.