Well no one outside of Ian, Jane and Bobby will face charges. I honestly can't think of a single example in real life where there has been 10 people charged with perverting the course of justice and faced prison or even suspected sentences.
We have to remember that the police may never know everyone who knows - why would they know Peter, Sharon, Phil, Cindy etc knew? They might know, but they are simply people that know the story, rather than are part of it - if Ian doesn't say anything about anyone then everyone will be fine. Despite a load of them indicating they knew something tonight!
Except Abi. She lied on oath about Max and was a big part of why he was found guilty. Even Jane lied trying to stop him going to prison. Abi deserves a slap on the wrist at least.
Jane is almost certainly an accomplice to murder. I do think it is technically murder, but they know Lucy had a number of knocks to the head so Bobby could get away with manslaughter - but he now has demonstrated and confessed to violent behaviour based on temper. So it's not quite accidental as he did intend to hurt her.
Ian is just guilty of perversion. If he hadn't let Max go to prison then he might have been able to argue grief etc kept him from turning Bobby in. But to deliberately let a man go to prison... I know it's horrid, but if Jane dies then he might get a suspended sentence.
I think Jane will die if I'm honest.