Half Scots here - and I use the microwave! I weigh the ingredients, using 60g of jumbo oats and 300g (= 300ml) of liquid (milk, water, or a mixture of the two) per person. Put them in a large (it will bubble up ferociously) glass or ceramic bowl with a pinch of salt and nuke for 8 minutes. Check and if too sloppy cook for a bit more in one minute intervals. I quite like it plain and cooled, my partner goes the whole hog with cream, golden syrup, dried fruit, stewed apple....
It is quite a good idea to add a bit too much liquid and cook it off; undercooked grains are not good for anyone.