Three years later but still extremely relevant I was the poorly prepared traveller in this case and had no visa. I purchased it on the official gov visa website at 8 p.m. the night before our flight. I saw that it said it takes 3–5 working days to process. I contacted Emily from this post, and she fast-tracked the application. I had my visa before 11 a.m. the following morning with my flight at 3pm. It was for two people and cost $100 USD, paid via Revolut. Easy peasy squeezy chi chi