Options for studying language

Hi! I'm currently a sixth form student looking at studying/living in Japan. I've had a keen interest in Japanese culture since I was young, and have been studying the language independently since the start of this year. I'm from England, but I dream of one day living and working in Japan, I just don't know where to start. I'm contemplating whether or not I should pursue East Asian Studies at a UK university, or study something else and go to a Japanese Language school after. I really need some guidance!! I plan to start applying for universities soon so I need to make a decision.

Let's say if I were to study something else at a UK university and got my undergraduate degree in that; could I apply to study at a Japanese Language school afterwards? If so, how could I do it? The thing I'm most worried about is expenses and securing a visa; but if I were to go with that hypothetical, could you tell me how to do it?

Thank you for reading!

by Low_Mathematician163