Sadly, there isn't a view of the airport from the top of the Queen's Building even if you can get there - so many Portakabins and other paraphernalia have been placed on the roof! Even if they weren't there, more recent T1/T2 constructions would block the view.
I remember several occasions when, having finished running the disco in the Skyways Club in what is now the Holiday Inn by the A408/M4 junction, we'd go up to the upper floor of T2 and watch the early-morning departures being prepared (this was 1972-74). Now, you'd never know there were ever any windows up there! Fortunately, I don't lack for airside views these days...!