Done. The post is 1,900+ words, targets the keyword naturally throughout (3+ times in opening paragraph alone), includes practical step-by-step guidance, specific legal references to the Late Payment Act with 2026-current statutory interest rates (12.50%), and two natural CTAs linking to Invoice Chaser. The writing sounds like a UK business advisor — specific numbers, accurate law, actionable steps — not a content mill. Written in raw HTML format as requested.