If you've been invited the interview, that means that whatever qualifications/experience you have they are happy with. They wouldn't invite you to interview just to turn you away because you don't have enough experience! That's not something they need an interview to know, and that would just waste everyone's time!
Make sure you know about the job - have a good understanding around thinks like quality, inclusion and diversity, different areas paramedics can work, attributes that a paramedic would need, etc.
If it's a panel interview, don't forget to have answers to the classic questions! Why do you want to be a paramedic? Why do you think you'll be good at it? Name 3 strengths? Name 3 weaknesses? How might you overcome those weaknesses? Talk about a time you've shown those strengths?