Dont expect a reply straight away though,
http://www.channel4.com/contact_us_t.html
It can take several weeks for them to reply due to volume.
Try these two personal email addies they were the press team for CBB7
Press Contact: Kate Conway,
kconway@channel4.co.uk
Picture Publicist: Charlie Fearn,
cfearn@channel4.co.uk
You might also want to get in touch with Endemol/Remarkable Television.