in 2016(ish) I changed an old incredibly noisy GRP up and over door to a Carteck insulated steel door. Back then it was about £1200 I think it – I fitted it with the help of a friend for lifting, it wasn’t difficult.
Very happy with it. It’s silent (we have a living room above), and it’s made the store room a much nicer place – warmer and cleaner.
Oh and removing the old door created enough space to put a mezzanine floor in which has given a ton of storage space.
Ideally it would open inwards and the larger door outwards
I’m not sure that’s possible because of the door sill – both doors would need to open the same way. Anyway, inward opening doors would rob you of some space.