Hi tom456
The legalities really depend on what you are importing and where you are importing it from as all goods being imported are given a classifications the Customs Tariff groups all goods into various classifications in order to arrive at a rate of Duty, so as i said it really depends on what your importing and where from and whether duty has allready been paid on it. for more information look here
http://www.sloanefox.freeserve.co.uk/index.htm
But whether you pay it as it comes through customs or not it may get differed and you will get a bill it the post sometime later requesting the amount owed for which you must pay without fail.
Hope this helps
Chris
AFBEnterprises