Nick can't have killed him - why would she have all the fingers and laptop etc, and why would her DNA be everywhere but none of his?
And why would the two of them be so suspicious of each other?
No, I reckon - she saw the bio photo and realised TI was right and Farmer had been set up. (Like Denton) she then set about trying to find out who was the real killer while also becoming aware that Hitlon was instrumental.
She then found out that Nick had lied about where he was when Leoni was killed and adding that to Steve questioning him and then being attacked meant she suspected Nick. So, knowing she had killed TI she decided to prove Nick's guilt with Leoni and set him up for the TI killing - so only one of them went to prison - hence her comment 'our children need one parent' (not 'my children need me' which I think would be a more natural thing to say?).
That way, he goes down for both, she gets to look after the (sulky unfriendly) kids. If she didn't set him up for TI death there was a risk he goes down for Leoni and she goes down for TI - leaving the kids parentless. She was delusional remember, with fever etc, but I think she sussed Farmer's innocence and Hilton's connection - she imagined the Nick part, but worked it out later when she got all the phone records (thanks to swot Jodie!).
Lakewell will get 2-4 years but be out for the next series.
H was Hilton in this context but Dot wouldn't have known who was proper in charge, so they have "Dot's H", but there is another H, higher up, and H is now just a code-name (like 'The Caddy' was, which was all because Dot met Hunter when he was a youngster caddying on the golf course for pocket money, and then later went into the police - 'caddy' is not a general term for a police insider I don't think?)
Agree her reason for not calling in TI death was weak, esp as he could have been saved. TI thinking she was dead was weak and him then deciding to cut her up - but I think we were supposed to just see him as a sadly lonely single guy who used prostitutes and had weird ideas.
The magical medical recoveries were far fetched but I could live with them.
Maneet is the unresolved thread for me.