The number eight made his comeback from a knee injury last weekend, and is included in a 24-man training party to prepare for the Calcutta Cup match.
Vunipola has been lined up to replace Nathan Hughes in the starting XV.
Scrum half Ben Youngs, wing Jack Nowell and centre Jonathan Joseph are also poised for returns to the backline.
Vunipola made his comeback ahead of schedule for his club Saracens on Sunday, after three months out with ligament damage.
And England head coach Eddie Jones appears set to bring him back at the first time of asking, after England's training plans on Tuesday showed Vunipola would start in the back row.
Bath centre Joseph, who was left out of the squad that beat Italy, is set to replace Ben Te'o at outside centre, while it's likely Youngs will be preferred to Danny Care, with Nowell edging out Jonny May.
England will confirm their starting XV and replacements on Thursday morning.
Jones' side lead the Six Nations table with three wins from their three matches.
Forwards (13)
Dan Cole (Leicester Tigers)
Jamie George (Saracens)
Dylan Hartley (Northampton Saints)
James Haskell (Wasps)
Nathan Hughes (Wasps)
Maro Itoje (Saracens)
Joe Launchbury (Wasps)
Courtney Lawes (Northampton Saints)
Joe Marler (Harlequins)
Kyle Sinckler (Harlequins)
Billy Vunipola (Saracens)
Mako Vunipola (Saracens)
Tom Wood (Northampton Saints)
Backs (11)
Mike Brown (Harlequins)
Danny Care (Harlequins)
Elliot Daly (Wasps)
Owen Farrell (Saracens)
George Ford (Bath Rugby)
Jonathan Joseph (Bath Rugby)
Jonny May (Gloucester Rugby)
Jack Nowell (Exeter Chiefs)
Ben Te'o (Worcester Warriors)
Anthony Watson (Bath Rugby)
Ben Youngs (Leicester Tigers)
Billy Vunipola will feature against Scotland in the Six Nations on Saturday, after being confirmed in England's matchday squad.