Calls are growing for a permanent memorial to the soccer legend whose career encompassed both the English and Italian leagues as well the international stage with Wales.
His family have asked Swansea Council to find a choir from the city to sing at the service on March 1.
Swansea-born Wales and Celtic striker, John Hartson - who wears the same No 9 shirt Charles wore on international duty - has called for their home town to provide a memorial to the man who was awarded the keys to the city in 2002.
And Wales' First Minister, Rhodri Morgan, has suggested a new stadium in Wales' second city could be named after him. "We have lost a great Welshman," he said. "There will be flags flying at half-mast in the minds of fans all over the world."
A book of condolence has been opened in the Lord Mayor's reception room at Swansea's Guildhall and is available for signing between 0900-1700 GMT on weekdays.