What makes Bottlehead instructions intimidating to a first-timer is how detailed they are: page after page after page of "do this" and "do that." But once you start building, all that detail makes the process easier, not harder.
Just go slow and check off each step as you complete it so that you don't inadvertently miss a step.
My first build was a tube-based guitar amp that came with parts, a schematic, and a layout (of components). No instructions. I figured it out, though there were many missteps along the way. I think my next build was a BH Foreplay III, which was a breeze by comparison.