When I was a university student, I majored in archaeology and really struggled with reading theses written in English. I felt that I was not good at correcting foreign information about archaeology.
Now I work as a clerical which is not related to archaeology at all, however, I’ve decided to make a comeback to studying it again one day.
So I have to improve my ability in English in order to prepare for my future.
I want to use English freely so that I can read and write theses when I return to as an archaeologist someday. soa natural?

"clerk" would be the job title, clerical would refer to something that a clerk would do or have

removed "as" because "as" is a current tense state of being, but the context of the sentence indicates its about the future.

removed "to" because it's a future tense / directional, but the context indicated you're talking about the time that you would do something, meaning that it's a current action that will be done, but with the timing being in the future.

Probably confusing, but the good thing is you are good enough to be at the very subtle nuance with tenses.