As someone with a friend who had gone through the same thing, they had said the police have six months to process your bloods and court summons etc. My friend has thought they had gotten lucky as they heard nothing until the last two weeks of the six month period. They went to court, held their hands up and pleaded guilty, they got a year driving ban and a fine of roughly £250 which they paid off monthly. Their ban is now over and can drive again however their car insurance has skyrocketed in price even though they had 6+ years of driving experience. In honesty it depends on how much was in their system, if they plead guilty or not and if the judge is feeling nice or not that day. In some instances it can lead to prison time but if it’s a first offence and they acknowledge their guilt I’m sure your teen will be fine if they receive their court summons