I once imported Dutas from Inhouse and paid £3.83 VAT plus £8.00 Royal Mail International Clearance Fee on top of the original £22 order. See the HM Revenue and Customs webpage - http://customs.hmrc.gov.uk/channelsPort ... _CL_001454
If they find its value is above a certain amount (about £18) there is VAT and also a few £ handling charge from the Post Office. I ordered 3 packets of Proscar and the surcharge when I picked it up from the Sorting Office was an extra £33!