Betty: Not sure if this is what you are looking for, but do you have "Magna Carta Ancestry" by Douglas Richardson?
He gives the Chauncey line starting on page 179 and has this to say about Joan and William: "Joan le Bigod, born in March 1339. She married William deChauncy, Knt. of Skirpenbeck, Yorkshire, and Stepney, Middlesex, son and heir of Thomas de Chauncey, Knt. of Skirpenbeck, Yorkshire. He was born about 1345. His wife Joan was a legatee in the 1388 will of her brother John le Bigod of Settrington, Yorkshire. He obtained a license from the King to alienate his manor of Skirpenbeck, and purchased considerable estates at Stepney. He obtained the manor of Pishobury (in Sawbridgeworth), Hertfordshire by lease. His wife, Joan, was living 9 Sept. 1398. Sir William de Chauncey was buried at Sawbridgeworth, Hertfordshire."
I haven't researched this yet, but there is apparently an article in the NEHGR Vol. 10 (April 1856) pp105-120, 251-256 by William Chauncey Fowler, "Pres. Charles Chauncey and His Ancestors and Descendants".