If implemented in a real, usefull way, they will work, if they are just another hoop added to the other hoops you need to jump through , they are pointless.
With international travel you have 4 issues.
What the airline will require for you to board their plane on the way out.
What the destination country require for you to be allowed into their country and spend time in their country without restrictions.
What the airline requires if you to board your plane home.
What the UK will require from you to return home and return back to your normal life.
If you have both vaccinations and a covid passport to prove that, if any of the above still requires you to have had a negative test within a month or less, then the passport is pointless, and us just another money making scheme that will do nothing but prevent the poorer from living their lives while the rich travel the world.