Far too many people on here fighting their corner instead of using their brains to suggest (just suggest,) ideas for amelioration. They would not all be good suggestions but one or two might come to something.
1. Perhaps a good part of the answer is already on here. The student is paying for instruction for the whole hour? Then maybe the instructor for early solos SHOULD attend in the tower to guard his students flight path and if necessary proffer the calming voice. (Mine did, but I did not know till after.)
2. We might recognise that student's behaviour during practice go arounds may not translate into clear thinking during an actual solo go around. Reaction during initial solos may be entirely different and it is really important not to deviate from practiced manoevres in these situations.
3. The removal of the PPL training for ATCOs in training seems incredibly shortsighted. There can be no better way to understand the environment, and in particlur how it feels for a student, that being one. Same thing for PPLs attending in the tower. Yes, I know it may be a distraction, but somehow those guys seemed to manage before.
When I was training at Kidlington there was a whole bunch of ATCOs doing their PPLs. We all used to wander up to the tower and watch the controllers and one of the ATCOs even took me to the LHR tower (they were encouraged to visit all the towers they could, including such as LHR,) ) I did not go on to a CPL but if I had I would have had some understanding of how airpspace worked and the incredible pressure in the tower. I think a few hours a year watching in various towers should be mandatory for, say, first officers and maybe even captains. OK it is creeping here a bit but I think it is relevant.)