After having a manic last few days to get the game finish, looks like Unity isn't actually going to export/compile the game quick enough for me to upload it. :-( It's taking FOREVER! :-(
Alas, it did finally compile - and upload - and get submitted too! But apparently there's an issue with the export as it doesn't seem to run (even though it ran find in Unity). Sigh. Apparently there's some Javascript error and it refuses to run. :-/