Mr Harrison, 39, started his marathon walk from Coldstream in Scotland on Sunday and hopes to reach the BBC Television Centre studios in London in time for Children in Needs Day on Friday November 18.
He is visiting children’s hospitals along the way and is seeking to raise around £5,000 in sponsorship and donations as he averages around 20-miles-a-day.
To date, his Pudseys Imperial March Just Giving page has raised more than £1,500.
Mr Harrison is hoping other Star Wars fans will don replica Star Wars costumes and join him on sections of the walk.
Mr Harrison visited the Great North children at Newcastle Royal Victoria Infirmary yesterday before heading to Durham.
He said: “I’m having a great response from members of the public. My feet are in bits but my spirts are high.” He added: “I want to coincide the date that I arrive at the studios to the big night of Children In Need to have as much impact as possible in order to raise as much as I can for this magnificent cause.”
Mr Harrison has modified the replica Darth Vader suit and installed two battery packs in the helmet to power a pair of computer fans to help him keep a cool head during the trek.
He is part of the 99th Garrison group of Star Wars enthusiasts who get dressed up as characters from the films and attend charity events.
He is writing about his walk on Facebook page Pudseys Imperial March. To donate, go to www.justgiving.com/fundraising/Gavin-Harrison3