I don't see how it can be the W as it's not one of the 6 letters that have to be changed. Must be the J but I don't know if it goes to the side or is part of the "description of the thematic setting". I have the activities, the nature of the theme, the geographical location, but am having trouble with 11ac, 13ac, 15ac (don't see how it fits the definition), 23ac, 37ac , 1dn (have the word, but can;t see how the clue works, and 29. All this means I think I know what is in the two side columns but I can't source the letters properly.