I would suggest that you contact the Customs Authorities in the country of destination regarding Duty Free thresholds.
Information on the Customs requirements for exporting is given in HMRC Public Notice 275. All notices can be found on our website www.hmrc.gov.uk under Quick Links > Library > Official Statistics – Publications – Notices, Info Sheets & Other Reference Materials > Import, Export & International Trade. The Public Notices are in numerical order.
HM Revenue & Customs
Customs International Trade & Excise