The United Kingdom (UK) Office of Financial Sanctions Implementation (OFSI) has published additional guidance on the UK sanctions policy in case of a no-deal Brexit.
This publication provides links to legislation and guidance on implementing UK and United Nations sanctions if the UK leaves the European Union without a deal.
The guidance may be found here:
https://www.gov.uk/government/collections/uk-sanctions-regimes-if-theres-no-brexit-deal