I love the oatmeal. I mix it together and cook it for 2 mins in the micros - give it a really good stir nd en continue for another 1 min. That normally does it for me although I'll pop it back in for another 30 secs if it isn't thick enough.
I add a tablespoon of wheat bran to mine too. This has the advantages of tasting nice (!), adding fibre to your diet and thickening up the oatmeal.