Hi, thank you for your message. To play a national anthem I need a midi or mp3 file as well as a sheet music.
In terms of practise, blue skies at normal speed is quite challenging, but I just called to say is more manageable. If you're a total beginner I'd say one year is a good time frame to look at with daily training before you can swing well, unfortunately chromatic harmonica is not the easiest instrument because of the needed precision and synchronisation between both hands and breathing.

But once you can play it, then most popular musics are easy, as most things, it's the beginning that is hardest when learning harmonica.

Cheers,
James