Hi there
With regards to Sarah, Percy's wife, since it would appear you have her maiden name and father's name and a POB, yes start at Scotlands People

Did she have an unusual or uncommon name - what was her father's name?
The CHANTRY family in 1891: in Grantham, Somerby, LincolnshireREF: RG12/ Piece 2586- Folio 12- Pg18
ADDRESS: 28 A Cecil Street - all surname CHANTRY
Head: William 26, Iron Moulder, b Derby Derbyshire
Wife: Emily 27, Burton on Trent, Staffs
Son: WIlliam 5, Scholar, b Derby Derbyshire
Son: Joseph 4, Scholar, b Derby Derbyshire
On 1901, which I guess you already have:
William snr says POB Heage Derbyshire
Emily says: POB Measham Derbyshire
Joseph & William , sons, POB Old Normanton Derbyshire
You would need to get his marriage to Emily (maiden name off Percy's birth cert) to hopefully learn his/their father's name, however this one looks promising:
1871 - ADDRESS: Prospect Farm, in Heage, DerbyshireREF: RG10/ Piece3588-Folio57-Pg27 - CHANTRY:
Head: John 60, Farm Bailiff, b Southwell Nottingham
Wife: Lucy 50, b Cole Handworth Notts
Son: Absolum 11, b Southwell, Notts
Son: WIlliam 6, b Heage Darbyshire
Servant: Henry JACKSON, unm, 16, Farmer's Servant (Indoor) b NK (not Known)
And in 1881: ADDRESS: Moss End in Mickleover DerbyshireREF: RG11/ Piece 2755-Folio 63- Pg31
Serv: William CHANTREY 16, unm, Farm Servant Indoor b Heage Derbyshire
In houselhold of George KENT, Farmer.
Cheers
AMBLY