Also, way I read it, (and open to more informed readings) is the bill lays the ground for the secretary of state to determine (alongside length of ‘probation period’) what, during this, would constitute fair reasons for dismissal and give guidance to employers about what they should have to evidence

And that there is scope for this to be a bit different in ‘initial employment period’ than afterwards. If an employer can evidence they have abided by these regulations and guidance this then the dismissal is fair. So it doesn’t preclude workers bringing claims for unfair dismissal from day one