With the UK leaving the European Union on 31st January 2020 there might be divergence of rules in the future between EU procurement and UK procurement rules.
At present the rules keep the same.
On top of that the WTO procurement agreement dispositions which are close to the EU rules still also apply to frame procurement activities. The UK having applied to join the agreement in its own rights a while ago.
Companies from the UK can still apply for any tenders issued by countries part of the WTO Government procurement agreement which includes the EU countries as well as EU countries overall for the time being pending trade agreement between the UK and the EU. For 2020 nothing changes. Beyond that we shall keep you informed.