If I were you, I'd try the Leavesden address for Emma. I wrote to her at christmas and received a lovely reply in March. Also wrote to Daniel there, but havent heard yet. Its been about a month now.

Hi !
I just want to ask , does the Leavesden Studios work when the film doesn't filming there ? I head that the movie may not be filming there next year and some casts , just like Emma Watson , doesn't have any other fan mail address . Then how can I send requests to them . For example , how can I send request to Emma ? Can anyone help ?