The government has released guidance on public procurement if there is no Brexit deal. The guidance addresses what will happen in relation to procurement opportunities that fall within the scope of EU procurement directives and which are currently advertised on OJEU via TED. 

The guidance explains that there will be a replacement UK-specific e-notification service to replace TED. Changes to the procurement rules will also be made through amendments to existing legislation. 

Here's a link to the guidance: https://www.gov.uk/government/publications/accessing-public-sector-contracts-if-theres-no-brexit-deal/accessing-public-sector-contracts-if-theres-no-brexit-deal