The band headline the bill of the special event in Hyde Park on July 27 with support from The Specials and New Order.
Asked about the possibility of new material being performed at the show, Coxon told BBC Breakfast: "Mmm, perhaps there might be some surprises. I'm not sure what any of the other people in the group have said.
"We all say different things and then we all get told 'don't say that' but they said that and getting into trouble."
He added: "But yes, there's going to be some surprises. We haven't made much preparations as yet but we've got to start rehearsing soon."
The band's bassist Alex James recently told Top Gear that the band would play a new song at the show, describing it as "like a hymn" and "a real tear-jerker".
> Read our review of Graham Coxon's new album A+E
Watch Graham Coxon and Damon Albarn perform new song 'Under The Westway' at the War Child show on February 19 at Shepherd's Bush Empire below: