I'd be interested to know how helpful/unhelpful supportive/not supportive the Yewtree officers were, if you're OK talking about it.
I phoned the NSPCC helpline first, who were extremely helpful and supportive. I was shaking like a leaf at the time, which surprised me. Then I gave a full statement to a police officer at my local nick, which was hard, because he wanted to know all the sordid details. After that I was interviewed by two Yewtree officers, a man and a woman, who were very sympathetic and didn't make me go through all the details again. Instead I gave them chapter and verse of all the complaints I made since 1991, with documentary evidence to support it, and the names of people at Springfield who were aware of it, including an executive director of the South West London and St George's Mental Health Trust I wrote to about it in 2005. It was not the only complaint I made against Springfield, who got my name and my personal history wrong in 1979. I had been trying to get my medical records corrected since 1995, so I had all the notes, which is why I was able to prove to the police that I had complained about Johnny Savile in 1991, as well as exactly what happened in 1979, including the date I was raped by that bastard.
Correcting the records proved impossible, despite several attempts to prove that I was never deluded about my identity or my background. I even tried to sue them as a litigant in person under the Data Protection Act! After the revelations about Johnny Savile, however, I have finally been able to convince the mental health experts that the story of my life is true and their version is fiction, by comparing it to the accurate contemporary account in the diaries my father kept for more than fifty years.
So from my point of view contacting Operation Yewtree had an extremely positive outcome.