What is the best way for me to acquire work experience?

I am a sixth form student studying Further Mathematics, Economics and Physics, I am hoping to study a course derived from mathematics at university, such as computer science or pure mathematics. I have been interested and utilised blockchain tech for last the two years. After university, I’d like to work at a disruptive tech firm focused around cryptocurrency and blockchain. However, I am struggling to find relevant work experience to help improve my chances of reaching this goal. I’m currently undertaking the Alchemy University Courses. Nonetheless, would anyone be able to give me some advice or recommendations regarding my dilemma (e.g website, communities etc.)?