Harvest is still regularly celebrated in UK churches, even those which are long-divorced from a direct connection with agricultural seasons, but unlike, say, Christmas, it is not fixed to a particular date (certainly within the Anglican church). On the Church of England’s liturgical calendar, the closest you can get is that Harvest Sunday is likely to appear quite a long way after Trinity but at least a few weeks before Advent.
At St Clement’s, we’re celebrating it on 6 October this year and I’m doing some work on a choral arrangement of Come, Ye Thankful People, Come which we might use as part of the service. Nothing too ambitious mind; we don’t have a big choir tradition so there’s no point dreaming up a 16 part motet. I’m thinking more in terms of unison for the first verse, outer parts (tune and bass) for the second, something a bit more crunchy for number 3 and probably either outer parts or full traditional four part harmony for verse 4.
That should be pretty feasible both to write (I’m almost there on the composing although I probably won’t manage to get parts done for tomorrow’s rehearsal) and to perform.