Mine has to be reallllly stodgy!
So I use less than 100 mls to start with and use hot waterso by the time i mix it up (usually the time i walk from my kitchen to my desk) Sometimes I have two packs together, and just every now and then top the water up as I eat it if i find powdery bits. every time i microwave mine it comes out horrible. I used to add sweetner too to mine (i know!!) but now its fine plain.
I haven't tried adding other flavours, but I know some in my old group used too, even if it was just a little banana or chocolate to give it a ready brek feel, but i love the porridge plain, so gonna keep at that now until I need a change.
Good Luck, and dont give up, always try making something different with your shakes, i love my chocolate ones with a spoon of coffee, vanilla with a spoon of coffee is delicious hot and cold.
Sometimes banana and choc together is good too! I sometimes struggle to get my packs down my neck, so I mix two together and have a larger drink.