In a small bowl combine the raisins and orange juice, soak overnight. Preheat oven to 180 degrees C. Grease baking trays.
In a medium bowl cream together the butter and sugar until smooth. Beat in the egg and orange zest. Combine the flour, bicarb soda and oats, stir into the creamed mixture. Fold in the raisin mixture by hand. Drop by rounded spoonfuls onto the prepared baking trays. Biscuits should be at least 5cm apart.
Bake for 8 to 10 minutes in the preheated oven. Allow biscuits to cool on baking tray for 5 minutes before removing to a wire rack to cool completely.
In a small bowl combine the white chocolate and copha. Melt over a double boiler or in the microwave, stirring frequently. When biscuits have cooled, dip each biscuit halfway into the chocolate then scrape the excess off onto the side of the bowl. Set biscuits on to greaseproof paper to dry.