Hi @markbutcher
“Lead” sheet as a term is often used to mean “piano” sheet and vice versa. A lead sheet does not have to be a piano sheet and a piano does not have to be used in the song. But what is most important for you is that you know how to read music notes written out on a music staff (most appropriate for blues harp is music on a treble clef – aka G clef – staff rather than on a bass staff).
If all of this is new/unkown to you, then it would help to learn about it before continuing.
Regards,
– Slim