I can't find any information about whether or not visitors to the UK are eligible for the booster vaccine (the person in question is 74 and has had 2 doses of AZ in their home country, the second one being 6 months ago). They will be staying the UK for the next 4 months.
The original two doses were available to everyone in the UK including visitors but for the booster, you need an invitation from a GP it seems. Would the best option be for the person register with a GP as a temporary resident and then request the booster? Or is there a faster way?