This year's annual series of events, which take place throughout November, will be used to formally announce Dench's involvement in the charity.
Sue Knight, appointed as head of PA last month, said: 'We are working out the details but will use the month as a chance to introduce her involvement in the charity.'
The involvement of the veteran actress follows the death of her husband, actor Michael Williams, last year after a long battle with lung cancer.
Dench's involvement comes as Knight seeks to increase celebrity support for the charity. Golfer Colin Montgomerie is another supporter as was Princess Diana.
As head of public affairs Knight also handles the lobbying work of the charity. She replaced Michelle Di Leo and reports to CEO Dame Helena Shovelton.