I believe that Wogan was being rehearsed prior to his live Saturday evening show, and some people saw him.
Did we get fed? Can't remember - I went to Broadcasting House twice, once with the late father of Mr Cloudhigh (I think we went to see 2001 at the cinema then went into Broadcasting House for lunch), and once with a neighbour (they were our 'party line' when we first moved to Amersham) to see the recording of a schools' programme he was producing, so I may have conflated the canteen at Broadcasting House with the one at Television Centre.
But clearly, even if the BBC weren't moving to Salford - and of all the things to move what sense does it make moving Five Live (if you are going to do anything for Five Live I would vote for getting rid of the news aspect completely and leaving it totally to sport - sport fulfills an important social function which is to give men something to talk about in pubs, which is more use than the hysterical, debased, nonsense that passes for news on Five Live on the whole) - the building is obviously going to be completely impractical for today's technology. It definitely has a look of the utterly unmodifiable.
Though I am with Charlie Brooker here - don't vajazzle our memories, better to flatten it.
I do feel though that there is a general sense in which the age of 'independents' (and I think you have all been bored by my views on them by now) and 'casuals' that a certain serendipity has been lost. Interesting things happen when interesting people can bump into each other. Maybe it is another element of Oldthinkers Unbellyfeel Ingsoc, and Twitter feeds etc. are a substitute but I kind of doubt it. What is wrong with the weekly meeting where anyone can turn up and brainstorm Weekending sketches? Why did it go? Perhaps some corner of Facebook is a substitute but does the current output suggest it is?
(as far as architecture-as-architecture goes, I not so sure about the 'keep a tiny bit of buildings and flatten the rest' theory in general. Both the Radcliffe Infirmary and Old Gaol (always spelled that way) have had more demolished than I was expecting, and I an not entirely convinced keeping the rest was particularly worth it in either case. Suspect that we save the wrong sorts of buildings in wrong proportions and should be concentrating on building better new ones).