The first-year professional links up with the Evo-Stik Northern Premier League Division One South side until the start of 2018.
The 18-year-old joined the club from Reading's category one academy before completing his two-year scholarship with United. He then penned his first professional contract in May 2017.
Sackey arrives at the oldest football club still playing association football ahead of their first game of the season away at Carlton Town. They then host Loughborough Dynamo three days later.
