How to get into law as a non law student?

I’m an upcoming political economy BA student at KCL and I’m wondering if it’s possible to get law internships as a non law student. I know you can get a GDL postgraduate but I heard that law firms can fund your GDL if you get a training contract with them. But how do I reach the point where I actually have a training contract with a law firm? I’ll be going into first year with absolutely no experience at all so I’m wondering what steps am I meant to take each year to ensure that I’ll have a training contract at the end?

Btw, I’m studying political economy instead of a straight up LLB because my parents thought it would be better if I study something that isn’t related to law to keep my options open 😭