Why did you miss your turn off? Why not brake and turn off behind him as you saw the junction countdown markers. Why this obsession with overtaking as many cars as possible before exiting the motorway?
Hmm what to suggest.. are you sure he's too young? Call the police - but film it first because many just deny any wrong-doing. Also, please take note of the following:
A long shot but... Does anyone know the name and address of the owner of this car? Ford Fiesta FN56 FKM? He hit my stationary vehicle in Cardiff on Friday at around 5pm. He mounted the pavement to try and cut around me but hit my car in the process. After gesturing to me he drove off but I followed and eventually made him stop. He called me a c*nt and with his female passenger railed against me, refusing to listen or give me his details. He isn't answering his insurer's phone calls at present and has left me with approx. £500 damage which includes a damaged parking sensor. I may need to take recourse to small claims court if he persists in avoiding his responsibilities. What a lovely young couple they are - mummy and daddy must be so proud. Again his reg. is FN56 FKM.
Fog-lighting bright in the normal non-foggy weather. Another muppet or a car with suspect electronics problems - who knows?