In the event of the UK leaving the EU with a negotiated agreement, the UK and EU have currently agreed that existing international agreements would apply as they do today for the duration of the implementation period.
Nevertheless, we have been working with our trading partners to have bilateral agreements ready in place for when we need them, whether that is after an Implementation Period or for a potential No Deal.
We are making progress and have signed or agreed in principle agreements with 32 countries. Total trade in 2018 between the UK and these countries accounted for 63% of the UK’s trade with all the countries with which the UK is seeking continuity in the event of a potential No Deal.1 That has moved from 28% since March. A regularly updated list of agreements signed is available on GOV.UK. https://www.gov.uk/guidance/signed-uk-trade-agreements-transitioned-from-the-eu
1 The figures quoted above are based on total goods and services trade (imports and exports) with the UK, according to the most recent data (ONS, 2018). They cover 65 countries that are party to 35 agreements. These are the countries covered by existing EU agreements in force in 2018. As above, this excludes Turkey, Andorra, San Marino which are part of customs unions with the EU and Japan, as the Economic Partnership Agreement only came into force on 1st February 2019