The short answer: direct sale vs marketplace sale is the fork that changes everything
<p><a href="https://www.gov.uk/guidance/vat-and-overseas-goods-sold-directly-to-customers-in-the-uk">HMRC's guidance</a> is clear on the two routes:</p><ul><li><strong>Direct sale (your own website, Shopify, WooCommerce):</strong> for consignments of £135 or less outside the UK sold direct to UK consumers, the seller must register for UK VAT and account for supply VAT at the point of sale. No registration threshold applies. The obligation exists from the first sale.</li><li><strong>Marketplace sale (Amazon, eBay, Etsy):</strong> the marketplace is the deemed supplier and accounts for VAT on eligible sales. The seller is not liable for the VAT on those sales.</li></ul><p>The same seller can have both direct and marketplace sales with different VAT treatments applying to each channel simultaneously.</p>