Sadly my drama was in a borrowed automatic so no clutch and whilst clearly I had to turn the engine off I wasn't sure what the auto box was going to do (answer: emit large amounts of smoke but apparently suffer no lasting damage). It was also on a dual carriageway, so 70mph but happened just before the start of a long hill down to a busy & backed up roundabout.
A surprising number of people have said that they wouldn't know what to do if they had been in that situation. I usually suggest that being in that situation tends to clear the mind quite rapidly, and I'm sure they would cope
Edit to add: In your example, dipping the clutch would just get the engine bouncing off the rev limiter and would probably freak people out even more. Just turn it off, if your breaks are as good as a Clio then you will need every bit of engine breaking you can get as things like ABS and power steering are now turned off.