Is it not wise, financially and in terms of time, to make that decision before you apply, though? Why rush into a medical degree to then change your mind and do IB later (or vice versa). Have you done work experience and volunteering in a care environment to see if it's genuinely what you'd be interested in doing? I'm not trying to say, contrary to what some people imply I'm saying on here, that you can't do both or that "everyone makes decisions at the same time". What am I saying is that it's a good idea to make that decision before you go ahead and do it.
You wouldn't buy a £250,000 house on a whim before even seeing it, would you?