I guess they are not open due to COVID maybe? Non-essential business... But it's essential to me... ??
According to a post yesterday evening (around 20:00) on their Facebook page: 'Items are currently off the website as we are adjusting pricing so VAT will now be applied at checkout 20% for UK and 0% for EU.' I'm assuming that'd ended up taking longer than expected, but for future reference Tuesday and Sunday are their regular 'closed' days.