I’m not 100% sure but to start on the path you need to complete a medical degree. To move up the prfoessional ladder takes many years of experience and more exams. I work with pathologists who are medically qualified doctors and it has taken the consultants I work with about 16 years to become fully qualified consultant pathologists. I would imagine it would be the same for any speciality you wish to go in to.
You can always contact you local hospital and see if they do work experience, this way you can see first hand what it’s like to work on a ward and you’ll have the chance to meet a huge amount of healthcare professionals all at different stages who can probably give you loads of advice.