Can anybody suggest from previous experience/recommendation, what is the best product for removing tear stains and whitening the coat around the mouth...

Also, where is the best place to buy it from preferably online but stalls at champ shows would be ok.

Try this previous thread

http://www.champdogsforum.co.uk/cgi-bin/board/topic_show.pl?pid=782640;hl=tear%20stains;hlm=and#pid782640

Thankyou.