I agree with all of you. I think there is much more to this story that has not been made public.
In the first instance, it is rather unusual, imo, for the police to take such a heavy interest in the disappearance of a 51 year old woman, who has left a note saying that she was going away as she needed some time to herself. I would have thought the more usual response would be to tell the family that there is not much they can do, but instead they seem to have done a large amount of searching and checking.
Re the cottage in Broadstairs Kent ( which is actually not a cottage as such, but a mid terrace house in the town ) there is a bit in the article that says the police have searched the property and also spoken to neighbours, all of whom say the last time they saw Helen at the property was Easter. So clearly she did not go there.
snipped from article
Officers have interviewed neighbours in Broadstairs and Royston, searched both properties and even drained the cess pit in her back garden in Hertfordshire.
Possibly she used the cottage explanation as an excuse, hoping that no one would try to contact her if they knew where she had gone but had actually planned to go elsewhere.
Or perhaps she did intend to go there but then changed her mind en route.
From Royston to Broadstairs is a fairly easy journey.
Train to London ( Kings Cross ) is 48 minutes with a frequent service. Then a very short walk to St Pancras Station ( London ) and train from there to Broadstairs is 1 and quarter hours.
From Broadstairs station to the cottage is a 7 minute walk.
But, so far, no sightings on CCTV which is just not possible surely if she was taking a train ( or even a bus ).
The only way I can see that she departed Royston would have to be in a car ( obviously not her own ).