Emma Whittington, aged 24, from Frant in East Sussex, will use 11 horses from Bedgebury Park Equestrian Centre in Kent, where the attempt will take place, as well as borrowing some from friends.
Not only is the event manager raising money for the charities but also she hopes to set a new world record, surpassing what she believes to be the current one by four hours.
Her 28 hours of continuous riding, starting on 17 September, will consist of hacking, schooling and a dressage competition on Sunday.
Any time spent transferring between horses will not be counted.
Emma, whose cousin, the eventer Francis Whittington, did a 24-hour charity ride in 1997, said: “One of my biggest worries is the boredom. There will be a party in the evening to help entertain me and on Sunday I’ve entered a dressage competition on three horses, so that, along with some hacking should keep me going.
“The other issue will be getting saddle sore — I’ve been riding all my life and done plenty of sponsored rides so hopefully that will help.
“I’m hoping that as I have to change saddles, and horses, about 24 times they will be kept to a minimum.
“Saddle savers and extra padding will also be used, I’ve already booked in a massage and acupuncture for Monday morning!”
Well wishers can join Emma at Bedgebury, on the evening of 17 September, for a hog roast, rodeo bull and disco as she rides. Tickets cost £10 and can be bought from firstname.lastname@example.org
Hospice in the Weald provides specialist palliative care, advice and clinical support for people with life-limiting illness, their family and the bereaved in the West Kent and East Sussex area.
Cancer Research UK works to find new way to prevent, diagnose and treat cancer.
You can also donate via Emma’s fundraising page at http://www.justgiving.com/teams/Emma-Whittington-28hourride