Career for plans for my future- enquiries to the experienced

In brief,
I am currently doing my (i)gcse's- high school level KS4
My plans are to major in dentistry (not sure as things can change) or in genereral in the science's sector.
I'm going to do my alevels probably take bio+chem+engfl, which lead me to my next point
My school offers pearson BTEC qualifications (only IT and HSC)
I'm really interested in IT and I guess I kinda really want to learn how to programm, and become more adept to the technological world on a deeper level of sorts..
But I'm wondering since (hypothetically) I'm studying dentistry, do you thinks it's convenient I choose hsc as it's more contextual for a dentistry undergrad or a health care career in general, does it matter at all if I deviate a little to pursue a unrelated study just to give me more insight.
I might not even complete the btec to diploma level just level 2&3
I'm not in a rush to make a decision I would just like to get other opinions on this topic.
Ps: Does it sound obvious of how naive I sound? Hlp a girl out.