Lots of stuff up at the BBC Writers Room site for Survivors: an interview with series (re)creator Adrian Hodges and another with series writer Gaby Chiappe.
Elsewhere on the BBC site, a fascinating (well, if you're into SF and telly) archive of Doctor Who development notes from 1963, including a report into whether the BBC should be getting into SF at all (conclusions: the Americans have all the suitable material, and SF isn't actually as popular as Westerns anyway), and some audience reports on Who's pilot episode 'An Unearthly Child'. This focus group stuff goes further back than anyone had ever suspected. I'm too scared to look at it just now, in case the word 'aspirational' is in there.
UPDATE: pilot script now up for download.