
Depends on the outcome of BREXIT. As far as I am aware(from a bona fide DEFRA source)the law for dogs coming to the UK isn't going to change, however for dogs going to the EU
may need to have a health certificate within a specific time before travelling plus a positive titre test if the UK becomes an unlisted country under the European Pet Travel Scheme.
To give yourself safety for your travel you may wish to first to titre test & if a positive result your dogs passport will continue to be valid, I would do this fairly soon. If the titre test isn't postive then revaccinate & titre test 30 days later.
As far as I am aware few dogs failed to get a positive titre test after vacvination & of course once you have that positive titre result it doesn't need to be done again as long as the revaccinations are done in time.
The UK government can apply for listed status after BREXIT( or include it in the BREXIT deal)& then there will be no need for titre tests as the UK is classed as a rabies free country.