Thats a shame. If you work full time, it could be a problem. Are there any other dentists at your practice who could supervise and help you? If you work part time or if you have one day off, maybe you could go to another practice?
Who are you doing the course with? Can they help? They may be able to suggest something.
I did mine with BDA who have been very supportive. And fortunately my supervising dentist was supportive also, so we chose 6 patients with appointments coming up, who I was familiar with, planned together, and made their appointments a bit longer so I could do my OH with them at the start of the appointment. Maybe this approach could help you if you're able to go to another practice once a week? You could also do your OH display there if they agreed?
You are right, you can deliver the advice to family and friends. But all sessions have to be signed off by your witness as this ensures your advice is correct and suitable for the individual.
Hope it all works out.