Don't sell yourself short in thinking you're not capable of something before you even try. Clouds look complex to draw, but they just take a certain technique.
I lean towards more of a cell-shaded style, with little to no dither, but despite, you're making it work alright. At 1:1 view, the clouds looks well blended. The car not so much.
I don't really "get" the piece. The way it's cropped is odd, I guess it has significance somehow. Shouldn't it be "H ♥'s K"? (with the apostrophe + s)