1. Preheat the oven to 180c.
2. Grease a swiss roll tin.
3. Put the oats, flour, sugar and bicarb in a processor with a pinch of salt.
4. Process briefly, add the butter and process again until the mixture begins to stick together.
5. If you don't have a processor you can use your hands to rub the mixture together.
6. Put 3/4 of the mixture into the tin and press it down.
7. Over a low heat heat melt the toffees into the milk and stir until smooth.
8. Pour this onto the base and sprinkle the rest of the oat mix over the top. Bake for about 20 minutes until golden. When cold cut into squares.