No one really knows. I think they intend on them being used in all countries but their main focus is the US right now. If I had to guess, it will take a few more years before we see them on the roads in the US and likely 5+ years before we see them outside the US.
Tesla mentioned rolling them out in 2023 but with the shortages, don't expect to see them until 2024 at the earliest and that is within the US only. I don't know when we will see them in the UK.