The UK Office of Financial Sanctions Implementation grants licences (exceptions) to some UK sanctions measures (including asset freezing prohibitions). The Sanctions Act providing the legal framework for licensing is here.
Guidance on UK licensing is as follows:
The application form for specific licences is here: OFSI Licence Application Form
The General Licences published so far are:
Export control licences permit prohibited activity under trade sanctions and embargoes. For details see: