Denise will be walking between 6-10 hours a day for a week to raise money for The Royal Marsden Cancer Charity, which helps the specialist hospital provide cancer care for patients.
The Magic FM radio host and former Strictly Come Dancing star, 39, is doing the trek in memory of her best friend's father, who passed away from leukaemia last year.
Earlier today (3 September), Denise thanked Lee - who she split with in July - after he and their daughter Betsy made a donation to the cause.
A very generous donation from @leemeadofficial and my gorgeous Betsy. Thank you so much! Xx— Denise Van Outen (@denise_vanouten) September 3, 2013
Taking to Twitter, she said: "A very generous donation from @leemeadofficial and my gorgeous Betsy. Thank you so much! Xx"
Denise and Lee, who met on the TV show Any Dream Will Do in 2007, were married for four years.
Announcing their split in a statement, Denise's rep said: "Denise Van Outen and Lee Mead are sad to confirm they have decided to separate.
"The couple remain the best of friends, with their daughter Betsy as their number one priority."
To sponsor Denise and her team, click here.