I dont know if i am qualified to answer this.
I was an actuarial student as well. Graduated last year, but I didnt undertake further professional exams. I passed the first three exams and earned all the exemptions (3 i think) under SOA exams during my school years. I am fascinated by quantitative finance during my studies too and decided it'd be best that I continue with posgraduate studies, if i want to focus on QF.
The reason I decided to switch it's because I feel like the exams are business focused instead of mathematical focused (it's a weird reason I know). Quantitative finance is a huge field, you won't experience and understand everything even if you study for your whole life. I passed ST6 equivalent exam in SOA (got a 9/10 score). What I can say about the paper is that it's all about methods and tactics. It's memorizing focused in my opinion, if you have seen the question and done it, most likely you'll be able to do it in the exam. I really hate that about actuarial professional exams. For quantitative finance wise, ST6 is just a really really small portion of quantitative finance.
Just some heads up, there will be much more difficult material in your future exam papers that involves in stochastic calculus (i finished some of the recommended books). But that too, I feel like it's insufficient to my study in master. It's all about what you want to be focused on, for actuarial profession, it's business focused. You learn what you need and apply it, most likely you wont be able to push the boundary of knowledge in quantitative finance with the knowledge of just professional papers. There's a profession in the industry called "quantitative analyst", look it up, it pays better than actuaries but typically requires postgraduate degrees in math, computer science, stats.
just my 2 cents contribution