I was in court last Dec and he was found guilty 30-odd years after the offending by a family member. I was the only complainant.
Would I do it again? Probably, but it's a tough and long haul through the police/CPS/court process (I first reported in spring 2015) with no guarantee of a guilty at the end, even if it gets to court. Think long and hard about why you are doing it, what you want out of it, how you will cope if you don't achieve what you want, etc. Whatever you do, do it for the right reasons for you.
I must say I cannot fault the police team though, they believed me and supported me right from start to finish - at each step along the way they checked if I still wanted to continue and there was no pressure to do so. I think all forces have specialist sex offences teams now, they were very good and really got how hard it was to speak out.
From my point of view, initially I just wanted the crimes logged so that any children he comes into contact with might be protected and for him to squirm through a police interview - I honestly never expected him to be charged and prosecuted.
Sitting as I am now, with a guilty verdict, I'm glad I did it. I feel like a huge weight has been lifted and I can finally move on. I've got a degree of closure, but it's still not something you ever get over really. But I'm well aware not everyone can achieve this.
f you are the sort of person who likes to read up on stuff first, I found this really useful.
rightsofwomen.org.uk/wp-content/uploads/2016/11/From-Report-to-Court-a-handbook-for-adult-survivors-of-sexual-violence.pdf
Happy to answer any more specific questions you have.