GolGotha
Death Scythe
You'd have to go via Viz USA as the UK branch just distributes
On their website it says
2. Can I submit my story ideas/manga for SHONEN JUMP?
At the present moment, all of the manga that appears in our magazines come directly from manga that has been serialized and published in Japan.
3. How can I get in touch with a manga creator?
You can send in fan letters to our office and we'll do our best to forward them along to the manga creator. Please send all mail to:
SHONEN JUMP P.O. Box 77010 San Francisco, CA 94107
On their website it says
2. Can I submit my story ideas/manga for SHONEN JUMP?
At the present moment, all of the manga that appears in our magazines come directly from manga that has been serialized and published in Japan.
3. How can I get in touch with a manga creator?
You can send in fan letters to our office and we'll do our best to forward them along to the manga creator. Please send all mail to:
SHONEN JUMP P.O. Box 77010 San Francisco, CA 94107