What is the very first step you should take if your commercial vehicle breaks down on a UK motorway hard shoulder?

1. Attempt to change the tyre yourself immediately
2. Pull as far left as possible, turn on hazard lights, exit the cab via the left-hand passenger door, and stand behind the safety barrier
3. Stay in the driver's seat with the seatbelt fastened
4. Walk back down the motorway to warn oncoming cars