Portugal is in the EU, and as the UK has left the European Union, there are more complex rules to consider when sending a consignment. Both an EU and UK EORI (Economic Operator Registration and Identification Number) are required to send goods from the UK to Portugal. Both numbers are vital and allow customs officials to trace shipped cargo coming into the EU from the UK. Failing to organise both numbers will result in customs blocking goods and holding them at the border, incurring fees and may even mean they are turned back. Be sure you are compliant. Take a look at the application process here: What is an EORI Number.
Further paperwork will be required to ship goods to Portugal from the UK, without which shipments will face delays, and border agencies will charge more fees. If paperwork is incorrect, customs may turn back goods, so giving customs the correct information is crucial to get it right the first time. Visit the government advisory page to get started.