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................ it feels like the door is more to contain the fire in the flat than stop one getting in.
Yep, that's pretty much the gist of it, the idea is to restrict the spread of fire by sub-dividing buildings into a number of discrete compartments. Yours and the other flats are compartments, the communal hallway is the risk or potential spread area and your fire door is the only barrair to that area, be it inwards or outwards. As I said, the ideas is that the fire brigade will get you out of your compartment before the smoke gets you, or as you say you'll be out the window before it's too late. But I'll add to my previous comments.
If you do go out of the window, or, and this is worse, some hero tries to break down the front door and attempt a recuse just watch out for one thing, that sudden rush of fresh air into the building. The fire, it may have looked okay the fella said and I reckoned I could get through that he said, but starved of Oxygen........, now someone opens the front door. Big inrush of fresh air and oomph and all that. Trust me, people have been killed because of that.
BTW Three hinges, cold smokes seals and all that, it ought to be standard spec on a fire door and if they hang the door with two of the hinges near the top and one at the bottom, rather than spread out equally don't worry about it, that's the correct way of doing it. Oh, and make sure they are proper steel hinges, not brass or God forbid Aluminium.