I’m not convinced that the policy to tell all patients that they are going to die shortly is the right one
How ridiculous. How can you possibly believe that is a policy.
Patients do have the right to know if they want to know. They have the right not to know if they don't want to know. So these conversations should start with asking them how much they'd like to know. In my experience every effort is made not to talk about timelines etc if that's the patient's wish, or not in front of a family member of it's the family member's wish.
However there is a move to recognise people who may benefit from the kind of things Palliative Care services can offer much earlier than they traditionally do - ie catching patients in their last year of life rather than their last illness/recognising their likelihood of dying within the next year even if they don't have an obviously terminal diagnosis. This can improve their quality of life, help keep symptoms under control before they start, provide pre-bereavement services for family members who they are then familiar with for when the bereavement comes, allows GPs to access Specialist help early on, give advice with financing or arranging any care before it reaches crisis point. And if people are well and not in need of these then they can be taken off the books until they are needed, but they are then known to services and less distressing conversations have to happen in the already stressful last weeks/days of life.
These are all available whether the patient wants to know their prognosis or not.
It should all be down to what the individual patient wants to know. And if this does take the wind out of their sails and mean they would like to go sooner rather than later, I think that's a perfectly normal reaction, sad though it can be to see. It's wrong if that was thrust upon them but not an inherently bad thing, even if it saddens the patient, if they wanted to know.
OP, I'm so sorry you and your Dad are in this position. It sounds like he has some specific fears around dying and it may be worth asking if he can be referred to the Palliative Care services so they can advise on this and come up with a plan that prevents as much as possible any of the scenarios he is worried about (such as not being able to breathe etc.) When the time comes he deserves to pass away with comfort, dignity and in surroundings and with the people he has chosen. Wishing you all the best for whatever the future brings with your Dad x