Well, you could sing the traditional Holy Saturday chant, the Exultet. That would fill up almost your whole time, and then you could have tea and crumpets and go home. The Exultet is the marathon of Gregorian Chant. It can be beautiful, even when sung in English; but many of those who sing it aren't quite up to it. Our deacon slides off key by the time he gets to the part where we have to sing responses, and then people wonder why our responses are so weak.

But since you probably won't do the Exultet, might I suggest "Julian of Norwich"?
-Joe Offer-