If a miscarriage happens in the first 24 weeks of pregnancy, there's currently no entitlement to statutory maternity, paternity or parental bereavement leave, I believe people should be entitled to this regardless of when the baby was lost.
You may be interested in these active petitions
I lost my baby daughter at 20 weeks gestation. This was a devastating time. My employer was understanding and gave me time off. Not all employers do this. We should be entitled to time to grieve.