You're always allowed to bring goods of a certain value back home without having to pay any duty or import tax. But there's a limit on the amount of tobacco and liquor you can bring back duty-free, and some countries have separate limits for perfumes; for exact figures, check with your customs department. The values of so-called duty-free goods are included in these amounts. When you shop abroad, save all your receipts, as customs inspectors may ask to see them as well as the items you purchased. If the total value of your goods is more than the duty-free limit, you'll have to pay a tax (most often a flat percentage) on the value of everything beyond that limit.
Check ahead with the Department for Environment, Food and Rural Affairs if you want to bring a pet into Scotland.
Department for Environment, Food and Rural Affairs (08459/335577. www.defra.gov.uk.)
HM Revenue & Customs (www.gov.uk.)
U.S. Customs and Border Protection (www.cbp.gov.)