They will definitely have spoken to people who know her, absolutely no doubt in my mind. They've had years to find people and will likely have downloaded the entire public contents of her FB and that of everyone who knew her. When you think about the photos which have been published of her, the nature of them suggests that they were posted on FB by friends of hers rather than her herself. I'm guessing they have hundreds of pics of her and will have been waving cheque books under the noses of anyone who knew her for ages.
The problem we have as to what we'll learn, though, is two fold; if she's acquitted then we'll actually learn very little unless she decides to talk. Privacy rights and not wanting to be sued into the next century may hold the papers off publishing much and the police and CPS wont release anything for the same reasons.
If she's convicted then I have no doubt that all sorts of stuff will be published about her, it will be an absolute information deluge for years; papers, magazines, books, documentaries and films are inevitable. The problem there, though, is that no-one will know what to believe. As a convicted serial killer of helpless babies anyone will be able to say anything they like about her with no fear of being sued. It's essentially impossible to defame someone convicted of those crimes so who is going to sue?