In Sussex the wassailing of the apple trees is generally around the 6th Jan, but in Devon it's later (20th this year where I live). The reasoning behind this is that "Old Christhmas" is 5/6 January, and therefore Old Twelth Night is around the 17th/18th.

In my village there's a ceremony around the apple trees in the local orchard, with singing and lanterns, and a folk band (me and my mates) playing in a nearby hall. There's also morris dancing and a mummer's play, and storytelling. There are stalls selling local beer and local cider, mulled or plain, and pasties etc. It's run by the local primary school, and is very well attended (and usually very muddy).

Marje