We now know what the immediate future holds for public procurement at the end of the Brexit transitional period. In readiness for a no-deal Brexit in 2019 the Government set up Find a Tender Service (FaTS) as its own alternative to OJEU. Procurement Policy Note 08/20: Introduction of Find a Tender has just been issued confirming that FaTS is being dusted off for 31 December when the Brexit transitional period ends.
Other than that, the immediate changes to the procurement rules are minimal; with The Public Procurement (Amendment etc.) (EU Exit) Regulations 2020 making only minor changes to the procurement rules to replace references to EU institutions and processes (including OJEU) with their UK equivalents.
In the longer terms, the Government is promising "radical reforms" so do look out for our e-briefing on this.