Can I finish the mail with this sentence,

Question

Thank you very much for your cooperation. Have a good Easter.
or
I take/seize the opportunity to wish you all the best for Easter.
Best regards,

I included a sentence I need to translate:
Last week we did an interview (also we went for an interview) for a music magazine.

Answer 1

I'd be more inclined to end the email like this:

Thank you very much for all your help. I wish you all the best for Easter.

Best regards,

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Last week, we went for an interview with the editor for a music magazine.

(or substitute "publisher" for "editor")

The point is that you interview with a person, not with a magazine!

Answer 2

Better: ... with the editor of a music magazine.