Put oats and boiling water into a medium saucepan and stir to combine. Let oats sit for 10 minutes. Add the remaining ingredients to oats in the saucepan and stir again. Bring slowly to boil over medium heat then reduce the heat to a simmer. Cook for 10 minutes stirring often. Remove from heat, cover and let stand for 2 minutes before serving. Serve with warm milk and stewed rhubarb and ginger.
To make the rhubarb
Trim and wash the rhubarb stalks. Place all the ingredients in a heavy-based saucepan and simmer over low heat until soft and tender, approximately 7-10 minutes. Set aside to cool. The rhubarb will keep in a covered container in the fridge for 3-4 days.