judging by Kim and Denise's reaction in the pub last night after Bobby blurted out that he killed Lucy I would have said neither of them knew

There's a difference between those who know Bobby has been named as the killer of Lucy, either by himself or Max etc, and the much smaller number who actually currently believe it.

What has always been implausible is the way no one seems to have speculated or gossiped about it after Max shouted out his accusations as he was being arrested. And also the way Lauren, after workng up to going to the police to inform, just waltzed off to New Zealand without a further thought about it, with he father in prison - didn't even let Abi know.

Realistically Ian should be due for a very long prison sentence, together with Jane, if she lives, and a few more, and Max would succesfully sue him for everything he has. But it won't happen.

There is only 1 Way to go with this storyline

Jane and Bobby will go to prison but only for about a year. I reckon Jane will cover for everyone and tell them that she's the only one who knows. The rest will get off scot-free.