Question regarding purchasing items from UK and EU

This doesn't really help. In some cases duty is charged. In others not.
That has been my experience- with the same vendor: Hilditch and Key.
The purchases were several years apart. On my last one in 2011 no duty
was charged.

Are you visiting these countries in person or are your ordering them online/phone?

If you are visiting the countries, you can request at VAT refund at the airport. Depending on the price paid, you may have to pay import duty tax when you return back home.