I believe that you can do a course at any outfit that is CAA Approved for CRM. However, it makes a lot more sense to do one that is directed towards helicopters, if you can.
CRM originally arose in connection with multi-crew operations, and ways of improving the way they work together. Most non-offshore RW pilots are single crew, of course, so the multi-crew style CRM is less relevant. I did try to seek out guidance and information about "single crew CRM" a while ago for continuation training, but drew a blank with the CAA and others. The only thing I did find was a US seminar pack produced jointly by the FAA/HAI, but I could not get hold of a copy.
If anyone knows of a CRM course for single crew ops that deals with helicopters, it would be good to know of it.