A free trade agreement is to facilitate trade between the EU and Great Britain. It is not only about customs duties and bureaucracy, but, among other things, also about opening the market for companies and the production standards for consumers, the environment and employees.
On 23 March 2018, the EU heads of state and government declared their support for a free trade agreement with the United Kingdom. Such an agreement could be passed at the end of the planned transition phase that is expected to run until 31 December 2020.
A free trade agreement between the EU and the UK would mean that goods with British or EU origins would not be subject to customs duties or, depending on the result of negotiations, that these would at least be reduced as compared to the WTO customs rates in the movement of goods between the United Kingdom and the EU.
Trade without customs duties between the EU and the United Kingdom would, however, only be possible for goods for which EU or UK proofs of preference are present. The effort for procuring or compiling these certificates of origin may be time-consuming. Therefore, it should be critically questioned whether customs preferences actually do have an advantage. That means: If the rate of duty charged for your product is low, preference calculation and rendering proof may not pay off.