The coach was carrying up to 70 people when it overturned between Wheddon Cross and Timberscombe at about 15:15 BST on 17 July. An off-duty firefighter who was travelling behind the vehicle was able to start freeing passengers immediately.
A huge emergency services presence then descended on the area, including a number of air ambulances to transport those most seriously injured.
In total, 21 people were taken to hospital, with a number of children being discharged over the weekend, police said.