"I have very little understanding of chords, scales or harmony. Does that make my mission impossible?"
Not at all... this is the best way to learn an instrument in the beginning, IMO.
Get obsessed with a song or solo and delve into it so that you play it over and over and over. Even if some (or lots) of the notes are wrong it's still incredibly productive to your dexterity on the instrument to learn new things and repetitively play them over and over. The majority of my melodic dexterity on guitar (single-note stuff) occurred during the first 2 years of my playing, because I was transcribing Metallica songs and solos, and shred metal riffs and solos like Children of Bodom 3 hours a day.
And when I say I was "transcribing" I mean listening and memorizing. I wasn't writing anything down on paper. I had little to no knowledge of theory back then. I didn't know how to write music. I didn't even understand how to read TAB. I had never even heard the phrase "ear training." It was just me, my guitar, a cd player, and a remote control with a highly worn out rewind button.