Undergraduate coursework is mostly theory, so at the point where you are now, my advice is simply to do as well as you can in your coursework. When you get to the point where you can start to participate in your professors' research, look for opportunities among the theorists.
My experience is in the US, where there are not (with maybe a few exceptions) separate undergraduate tracks for theorists and experimentalists.
This was the second term of calculus-based freshman physics, using Halliday & Resnick's
Fundamentals of Physics as the text. Multivariable calculus was not a prerequisite, although I was in fact taking it at the same time.
We learned the integral versions of Maxwell's Equations, which can be explained pictorially / graphically. We applied them in very symmetric geometries where the multivariable integrals reduce to simple multiplications.
In the mid 2000s, when I taught that material myself, I called those integrals "Geico integrals": "
So easy a caveman could do them."
Later, in our intermediate-level E&M course using a text similar to Griffiths'
Introduction to Electrodynamics, we got the full treatment using both the differential and integral versions of Maxwell's equations, and applied them in situations where we actually had to use our multivariable-calculus techniques.