You will need to know your own commodity codes, CPC codes, and your products. Everything else is easy and user-friendly.
In order to make an import or export declaration in the EU, you need to have an entity based there. This means that if you are UK based, you can make a UK import or export declaration, but need an EU entity to represent you in the EU to make a declaration there.
Different countries have different port pass systems. Read our Port Passes for GB ⇄ EU Imports & Exports guide for more information.
Yes.
The software uses CustomsLink’s port badges, so there is no need for you to get your own.