I use this a lot and thought I would pass it on.

To be really efficient when herbs from America, or anything from anywhere abroad really, look up the current months exchange rate here.
http://customs.hmrc.gov.uk/channelsPortalWebApp/channelsPortalWebApp.por...

This way you can make sure you keep your purchases below the £15 threshold without fear of the dreaded letter from the courier company demanding import duties and admin fees.