Can I still undertake a work placement in the United Kingdom after Brexit?
Until the transition period ends on 31 December 2020 all EU agreements and rules apply to the UK. You can start a work placement in the UK before the end of the transition period.
The situation may change after 31 December 2020. This depends on the new rules in the UK and the agreements made between the UK and the EU. Depending on your situation you may need to apply for a visa.