Satsumas will face either Highmoor Ibis or Woodley Town at Madejski Stadium on May 22 after beating Flackwell Heath 3-1 last Saturday.
The Larges Lane side put in a superb performance to see off their Hellenic Premier Division rivals and move one step closer to winning Herridge's first trophy as manager.
Standing in their way will be either Woodley Town or Highmoor, who both play in Division One East and meet in a re-arranged semi-final this Saturday.
The two Berkshire teams have both enjoyed impressive seasons, with Highmoor gaining promotion after finishing second in the league and Woodley winning eight of their last nine league games to claim fifth spot.
"The final will be a hard match, whoever we play," Herridge told the News. "If you look at it on paper then we will probably be favourites, but it will be a hard game.
"Highmoor are a good side, and although they have got publicity for other things, they have some talented players. Woodley are also strong, they lost a few players in the summer but [manager] Cyril Fairchild has put together a good team."
With a couple of weeks until the final, Herridge expects to have nearly a full squad at his disposal for the match. And he admits that with the match being played at the home of Reading FC, it will be tough for him to pick his side.
"It will be hard for me to choose a squad let alone a first team," he joked.
"This cup isn't the biggest but we get to play in a Premier League ground and it's a nice way to finish a long season.
"It would also be my first cup as a manager as last time we were here it was as assistant to Wayne Wanklyn."