I've been watching that series on PBS here in the US over the past couple weeks - last night was a two-hour broadcast covering the Queen's state visit to the Balkans, the State Opening of Parliament, and an Investiture. What I found interesting was the "preparation" scenes where members of the household staff were scurrying around getting ready for this or that. That let's the viewer get a much better perspective of the palace than mere photos.
My biggest impression was the sheer scale of the rooms! One scene showed some courtier (I don't recall whom) walking the full length of the garden front - starting in the Royal Closet and continuing through the White Drawing Room, the Music Room, the Blue Drawing Room and into the State Dining Room - where the open doors to the West Gallery showed a continued vista on into the Ballroom. That truly gave a sense of the enormity of the space.
Another showed the Queen and Duke with a visiting president and first lady (Ghana I believe) before a State Banquet. It started with the funny scene in which the lift ddin't work and the first lady (who has trouble with stairs) had to be brought up on the luggage lift. Then it showed them all walking from the top of the Minister's Staircase into the little lobby at the north end of the Portrait Gallery. Having only previosuly noticed that lobby on floor plans as an inconsequential space, I was amazed at how large it truly was. All the palace housemaids were assembled there to meet the president, and there had to be 20 -25 people comfortably standing in that Lobby at one time.