At that age I wouldn’t bother sterilizing sippy cups, just bring dishwashing soap. If you’re set on sterilizing then check mothercare and boots for the cold water sterilizing tablets, they are easy to transport. Bring small boxes of UHT milk to keep in your cabin. Load up on familiar snacks. Bring inflatable tub or hold your kid and shower. Be flexible, but try to stick to your routines. I think you’re looking at this through the lens of an infant, but it will all be easier as your baby gets bigger.