This is more of a point about English grammar, but "what do you do this week" sounds incorrect. "What do you do" refers more to what you do regularly, always... restricting it to this week is contradictory.
Are you from Felvidék (for the learners: southern part of Slovakia where Hungarian is spoken)? "egy hét alatt" sounds unnatural to me. "hét közben" is another option though.
"Mit csinálsz a hétközben?"
"Kozben" means meanwhile, or chronologicaly inbetween.
Is "a héten" always implying that it is "this week"? Or can it mean in another context "during the week" (every week)?
What about "ezen a héten"? Would it be too much emphasize or redundant in Hungarian?