How do I become a paramedic?

Let me expand on my situation…..I’m interested in becoming a Paramedic but want to take on some work experience over the next two years to make certain I’m choosing the right career path.
I would have to take the “traditional route” into the role as opposed to the degree route as I’m alreading undertaking a degree in Cancer Biology and Immunology.
I’m hoping to join the St John Ambulance as a volunteer in October via my Students’ Union therefore, would it be advisable to wait unitl then to start applying for wrk experience placements? And also HOW would I go about applying for work experience? It’s obviously a tricky one being such an urgent and demanding role that I doubt they like students hanging around in their way too often.
Any info on how/when to apply for work experience, being a Paramedic or the traditional route into the career would be greatly appreciated!!!!
Thanks