Hi,
I have just been in that exact situation and was fortunate to have done something I think all Robinson pilots should do at least once in their flying careers.
I have recently completed the European Robinson safety course, taking 3 days 2 of theory and 1 of flying with 2 hrs of various drills not normally covered in "basic PPL training"
As this is my first post I do not want to break any advertising rules but a simple google search on European Robinson safety course will point you in the right direction. The instructor has 100% credibility being involved with the product since nearly the first ones made and has first hand knowledge of what exactly goes wrong by being the safety accident investigator for Robinson Helicopters.
It was an eye opener to get detailed and precise engineering and factory direct thinking on various components, checklist and flying techniques which for my part had been forgotten or missed in my PPL training.
The Course cost was 340 pound plus Vat for the ground theory part and the flying is variable depending what school hosts the course? (I paid 425 ++ per hour)
PM me if anyone wants the exact contact details and I hope this is of use and really made my issue of getting back into the right seat a very productive and valuable experience.