As you said before, it's highly unlikely she'd have been imprisoned here. I actually don't think she should do time for the collision. She wasn't pissed, speeding, or otherwise being a twat. This is a horrible accident which she's clearly absolutely distraught about and I'm sure most people who've driven overseas have found themselves momentarily on the wrong side of the road at least once or twice. This is to take nothing away from the devastation that Harry's parents must be feeling, but what purpose would putting her in jail for this accident have served?
What she should be prosecuted for is runnning away and compounding the pain she's caused the family whilst taking the piss out of the UK justice system.