Thanks, that seems to work way better than the app I used previously.
Now I have all the files, but no folders. Can you (or anyone) please confirm the naming convention of the save folder if in-game it was still called New World (in other words I forget if it was .New World or something, or can it be named anything?) then the folders I would expect to find inside, and a rough description of their contents? Pretty sure the files named R0.0.mca etc go in a single folder named "Region" and the long json file (is this my seed number?) sits on its own in the save folder, but not sure about the rest.
Thanks!
EDIT More specifically, I have along with the aforementioned json file and region files:
Seven files named map_(1-7).dat
Seven files with no apparent extension, names are a mixture of 8 alphanumeric characters
Two dat files with my usernames (although these are linked to the same world)
Additional DAT files named Fortress, idcounts, Mineshaft, Stronghold, Temple, Village, villages
...i thought there was meant to be a Nether.dat file or similar also, but could be wrong there.