Having looked it up and answered my own questions.

Yeah they are actually building a portable star.

And while it is very much an experiment. It is based on a smaller successful fusion plant from 2022.

So honestly using your guess. 7.5b 2045 and failing. Is still pretty fucking amazing amount the UK learns about a new future technology. And well worth the risk for the expertise we would gain.

If it actually works the UK will be helping the world make more. And the odds are pretty high compar d to the UKs first fission plants.