Are there any good books providing an introduction to the Hardy-Littlewood method that do not require much of a background in complex analysis?



Books on the Hardy-Littlewood circle method
The book I would recommend is Vaughan's **The Hardy-Littlewood Method** (Cambridge Tracts in Mathematics). I don't remember it (or the subject in general) using much complex analysis - only the properties of the function $e^{ix}$, really....


