Generally, UK photo card licence holders will not need an International Driving Permit (IDP) in order to drive in the EU/EEA after Brexit. However, you may be required to have an international licence in addition to your UK domestic license to hire a car in certain EU/EEA countries if:
-You do not hold a photo card licence (i.e. you have a paper licence).
-Your licence was issued in Isle of Man, Jersey, Guernsey, or Gibraltar.
You can easily obtain an IDP at your local UK post office. You can read more about driving in the EU after Brexit as a UK licence holder here.