Medical physics, do I bother?

I (27m) am currently a Physics teacher. I did BSc Physics at uni and got a first.

I do want to become a medical Physicist but it looks so damn competitive, even for people who actually have a masters and some relevant work experience - which I have neither of.

I guess my question is, how do I go about making the career switch? I probably wouldn't get accepted onto an STP for a good number of years, and if I really wanted it I would have to spend time trying to get work experience more closely related to the field - meaning I probably would have to stop teaching.

Sorry if this post is depressing lol. Just expressing my thoughts