R&E will close on the 28th December - see this thread. https://www.religionethics.co.uk/index.php?topic=22932.0#new
I think 'The Little Chapel' in Guernsey could be described as a grotto. It is worth visiting if one is over in the island.https://www.visitguernsey.com/magazine/the-story-of-the-little-chapel/