UAV ...... Good question, and hobbit sums it up with common sense and good practice, I would add duty of care, because if your student has an accident you are going prove in court that there was a duty of care in place.
Personally, I would say most exercises should be practised with the exception of the following:
1. Stalling, from the point of lookout in a high nose attitude and also accidental spin.
2. EFATO.
3. Steep turns, also due to lookout.
4. Sidesliipng (if taught), again in case of an accidental spin.
5. Instrument flying.
I could undestand if it was a club policy was no solo PFLs, because I have known a few instructors to mess up PFLs and EFATOs usually due to carb heat or accelorator pump issues.
All aspects of take off and landings need to be practised solo, flappless, glide, full flap. Although probably would not be unreasonable for a club to make full flap landing to full stop.
Again on the subject of duty of care, for any solo you need to ensure that the student has been trained in all the emergencies for the particular solo exercise. This does not always happen. For example I came across a student who was being sent on solo departures and rejoins, having not been taught PFL and all the inflight emergency drills. Likewise I have come accross students who have been flying solo have not been trained in all the emergency drills. As a consequence I have always had a supplinentary sheet they sign for each emergency, such as engine fire ground, engine air, electrical fire, electrical failure, engine restart.
I have to say I think some training organisations are becoming a bit cautious. When I started my civilian training a while ago, we used to do full single engine shutdowns (dual), raise the nose to the point that the prop stopped. engine restart without the starter motor, followed by a dive to windmill the prop to the point the engine starts. I was required to demonstrate this on my GFT, but it may have something gaining SLMG as well as PPL (A) priviledges. Can anyone confirm that? Also I did my night solo circuits for my night rating on a runway with compacted snow, again I'm not sure that in the UK thesedays you would send someone solo in these conditions.
UAV.. You might want to check additionally in the aircraft insurance documents to see if there are any restrictions in relation to student solos and if non compliance with the pilots order book invalidates the insurence. Finally, you might want to speak with your FIE, see what his/her take on this and then take it up with your CFI.