The gear - enough to fill 30 horse horseboxes - will travel in convoy this weekend to the premises of the International League for the Protection of Horses (ILPH) at Snetterton, in Norfolk, where half will be unloaded and stored.
A convoy of 15 vehicles will then continue to the premises of the Redwings Horse Sanctuary, also in Norfolk.
The 30 vehicles that will form the convoy will gather at Newmarket on Friday night, where they will remain until setting off at 8.30am the next day.
The donated goods were gathered by Operation Esther, so named after the youngest donkey rescued from the farm. Esther and her mum Mary were taken to Redwings sanctuary, where she was given her name.
It was set up by members of the Horse and Hound online forum to support the charities involved in caring for the Amersham horses.
ILPH, which is caring for 11 of the horses, estimates their care will cost £66,000 over the next year alone.
Operation Esther had its beginning when forum member Michelle Mortimer placed a plea on the site for people to give up a luxury and donate that money to the charities concerned.
"Everybody involved with Operation Esther and the collection of donations has really taken it to their hearts and we are all very grateful.
"It is brilliant to be able to help the charities who took in not only these equines, but take in rescued horses, ponies and donkeys all year round."
Her appeal became a nationwide movement that has gone from strength to strength, with collection points established around the country.
The beneficiaries will be Redwings, ILPH and The Horse Trust.
None of the charities are directly involved with Operation Esther but have expressed their thanks and appreciation to those who took part.
The ILPH is seeking volunteers to help sort through and clean the tack and other goods on Sunday.
"We have really been overwhelmed by the public show of support and are very grateful to Operation Esther and everyone who has donated for their kindness and generosity," said Tina Sales, Head of Fundraising.
"If anyone can come along to help on Sunday 27th January to help clean and sort through the donated items, we would love to hear from you.
"We will be holding sales of the donated items in the very near future and will let everyone know when so as many people as possible can come along to pick up a bargain and help raise essential funds."