We have just returned from LHR to Sydney via Singapore, travelling with a child and infant. Had 5 pieces of hand luggage including a Quicksmart pram (folds up into a backback), without drama's.
We were actually ushered to the front of the waiting queues to go through security, had no trouble taking food onboard, and bought water and milk 'airside' to avoid any drama's. I suggest you do that, with the formula measured out in containers in case they do confiscate the premix.
It seemed we were given special 'bypass the queue' priveledges because we had kids in tow (or maybe because we looked totally frazzled)
My travelling with kids motto...expect the worst and you'll be pleasantly surpised.