Heathrow - rules on formula and water thru security

[BexJ82]

We are about to take our twins (5m) on holiday for the first time (gulp). I'll need to travel with sufficient formula powder, cold sterilized water and boiling sterilized water (in thermos) for at least 12 hours (if not more in case of delays). I understand the rules on this vary from airport to airport - does anyone have experience of Heathrow T5 security? In particular i'm thinking they might object to the large thermos. The twins are on a prescribed formula so I have to take it in carry-on.

I'm sure someone will know better than me but just thinking about this. Could you ask in a cafe once thug security for boiling water? Take one thing off your list perhaps. We use a rapid cool which might work well for you as then you just need boiling water and don't have to have cooled. Though I did think that anything for baby was meant to be fine.