When do you turn?

[Paul]

The legal definition of a squatter is:-
An individual who settles on the land of another person without any legal authority to do so, or without acquiring a legal title.
So I'm reading that as if you move in, you're squatting.
The offence of squatting in a residential building now carries a maximum penalty of six months' imprisonment, a fine of up to £5,000 or both.

If you are just sheltering, your trespassing.
If you are trespassing and leave immediately when told, provided you haven't broken in, stolen or broken anything, the way I read the law is "No harm, No foul".
Of course if the plod is called, gawd knows what may happen.