In this TES exclusive, it says pupils may have to sit their GCSE and A-level exams on later dates or at alternative venues in the event of a no-deal Brexit.
The full article is behind a paywall, but a source has told TES that "you could literally end up with kids not able to get to school for their timetabled exams" if a no-deal Brexit causes significant traffic disruption.
Exams could be postponed nationwide if lots of students were going to miss it, and boards have apparently been arranging "alternative sittings" on later dates in case students are unable to get to exams - but might have to involve some students sitting a substitute paper of "equivalent" difficulty.
Why would a no-deal Brexit affect exam timetables?
the article talked about in the question states the possible reason as traffic jams so that many students may not be able to reach their examination center on time.
Government are not really thinking about those who are going to be affected. We, as this generation, will have to build from their mistakes, which I see as unfair