Very sad. RIP.
However, with the information that's been realised I'd go so far as to say that I'd expect the school to face some form of legal action for the lack of supervision.
They will have a student to teacher ratio to abide by, risk assessments and a duty of care to supervise and control the kids. Yes, the girl is responsible for her actions but as she is so young that legally the school will be expected to take more precautions for something like this. I'd fully expect the enforcement authorities to focus heavily on the school and the theme park to weed out the failure(s).
No doubt the HSE will be crawling over the park for the foreseeable future and the school will be sweating bullets as they're questioned. Let's not forget that the staff at Drayton Manor will be finding it hard to deal with, particular those in the immediate area/responding. Something like this will see staff in pieces for a long time.