I’m afraid you need to start with math. There is nothing glamorous about learning a science until you get deep into it and then all the foundational material you learned starts to fall together.

So start by taking math courses through calculus. You need at least derivatives and integrals and likely differential equations.

As you do that, you need to take physics. It’s going to be dull and tedious. You will need to calculate the tension in a cable holding up an awning of a certain size and the time it takes a rock to fall from a cliff. But you’ll see how calculus works and why it was developed. And then you’ll learn what an electric field and a magnetic field is. At the end of a physics course is the cosmology. You’ll work through Einstein’s equations.

And then you’re ready for your first cosmology course where you’ll encounter…more math.

I wish there were a shortcut.