I would think that to be part of the FDA trial, ba

I would think that to be part of the FDA trial, baseline testing would need to be done at a trial location. Since no locations exist in the UK, she needs to come here to begin treatment. After being started on leronlimab she might be able to go back, however there remains the question of required future testing to determine progress.
Compassionate use in the UK probably only applies to CV-19.