Hi Alison.
It is said to be an excellent film.
Ken Loach is an outstanding director.
I agree with your reservation about its truthfulness.
Not that what it portrays is not true, just that it is selective in what it shows and therefor unbalanced and biased.
But films are not history texts.
People should not go to the cinema to be educated, only entertained.
Enjoy the film,
Keith.