The Whites offer of £350,000 for the 24-year-old former Wimbledon hit-man has been accepted by Gillingham and the player is to undergo a medical at Deepdale.
"I would like to wish Patrick every success with his new club," Gills chairman Paul Scally told his clubs official website.
"In his short time at the club he showed potential and given a better financial climate we would have preferred to see him stay at the club and develop."