The day of the Queen’s death will be followed by a 12-day mourning period
The entire country will be in mourning for just under two weeks. During this time the Queen will remain at Buckingham Palace as plans for her funeral are made.
The Queen’s coffin will then lie in state in Westminster Hall for four days so that the public can pay their respects. It is expected her body will finally then be laid to rest in St George’s Chapel at Windsor Castle.
So this reminded me of the whole mourning process for the death of the queen. I apologize for the bad source, but it's the first thing I found when searching: https://thetab.com/uk/2019/12/02/what-happens-when-the-queen-dies-134218
The part I found especially interesting:
She's not allowed inside Buck House - even if she's dead.