Kates main address
Kate Winslet
C/O William Morris Agency
1325 Avenue of the Americas
New York, NY 10019-4701
U.S.A.
Other addresses
Kate Winslet
503 The Cahmbers
Chelsea Harbour
Lots Road
London
SW10 OXF
UK
Kate Winslet
31/32 Soho Square
London WIV SDF
England
I have heard the one above has really worked but I did not get any of them from reliable sources. I hope you get some kind of response!