I'm suspicious that it was actually a seizure. I think this should have gone to court, and there should be some serious medical evidence to prove that she's not guilty. She should NEVER drive again, either way.
Having said that, if it was a genuine medical episode, it raises questions about how appropriate it is to have 3-tonne SUVs around a school (or in cities), as a smaller lighter vehicle would not have done the same amount of damage, and why the motor industry isn't forced to have safety systems to prevent sudden accidental acceleration in place in new vehicles. The technology to prevent something like this definitely exists.
Unfortunately, this will likely just be written off as an accident and nothing will change as a result. Children's lives are cheap on UK roads. Most people are quite happy to sacrifice a few so that we have our excessively big cars and drive them as fast as we like, wherever we like.