Like everything in vaping it’s depends on a few things carrier , value , weight, what it’s classed as , we’re it’s from.
a lot of China companies ship the device to a third party in Hong Kong such as “ King De humidifiers “ then the items are classed as de humidifier parts and have a low value . Customs then tax it as that. You’ll then get a notification to pay import tax either from the carrier themselves or the import office at the holding station. Can be from £5 - £500
but I’ve had items sent that have sailed straight through end to end with no issues and have been classed as E cigs.
there isn’t a straight forward answer tbh.
Sometimes if a device has been sent to me I’ve been notified by ups that they require an ECID number and £12 tax for 1 device.