Just watched the documentary, although I felt it was too soundbite and not enough depth. I'd have liked Hammond to have gone a bit more in depth into his thinking behind some of the stories, especially "The Girls who gave them Flowers" ...
Quatermass. Me, I'll work my way through in order, although I don't have the third film and I don't consider the John Mills one as it's not BBC. Whatever works for everyone else is fine - I just suggested a free for all to give everyone a chance with what they have in their collections, although I was planning on watching the surviving Experiment episodes to give some context.
There's also the Hammer film "X the Unknown" which they wrote as a Quatermass until Nigel Kneale told them to feck off nicking his IP and they redid it with a different boffin. It's actually rather good, although a bit creaky. Fun fact - it also features a young Frazer Hines.
At a real stretch, there's the audio serial "The Slide" by Victor Pemberton, which was allegedly written for Who but David Whitaker rejected it, so it got reworked as an audio, made by BBC radio, and then Pemberton rewrote it yet again and resubmitted it as "Fury from the Deep". Fun fact - Roger Delgado is the Doctor substitute in The Slide.
"It's basically a cure... for not being an axe-wielding homicidal maniac... the potential market's enormous!"
"Please dial *617 at this time"
"We're the Sweeney, son, and we haven't had any dinner!"
"Don't be told what you want. Don't be told what you need." - John Lydon