Complex sentence: The choir normally sings the 6:30pm service, or occasionally one of the other Sunday services as well as special services including the Christmas Midnight Eucharist and Carol Services, and also regularly joins with the Cathedral Choir and the Cathedral Chamber Choir.
Split into simpler sentences: The Choir normally sings the 6.30pm Sunday service, or occasionally one of the other Sunday services. At certain times of the year the Choir sings special services including the Christmas Midnight Eucharist and Carol Services, and also regularly joins with the Cathedral Choir and the Cathedral Chamber Choir.