I don't know whether those who have been posting recently were not following this case from the start. In which case they might have missed the press conference by Superintendent Riley on 3rd February. She stated very clearly that they had considered all the factors around NB herself and that their main working hypothesis was that she had fallen ACCIDENTALLY into the river. In the Q&A session she even mentioned how it was possible that NB had gone to attend to the dog, placing the phone on the bench, and had then fallen whilst dealing with the dog.
There has never been an occasion I'm aware of where police have described a hypothetical accident in such detail if they had found any reason to consider suicide to be an equally likely possibility. Ergo, IMO there was no 'note', and no need to speculate about what happened on January 10th. If the inquest reveals otherwise I will admit to being wrong, but in the meantime I don't think it's kind to her family for people to keep speculating.
superintendent Riley press conference