Hi, kayjay. I have been hospitalized twice; once for 3 days, the other for 3 weeks. Both times I went in voluntarily. It seems like you may be considering going in on your own; if that's the case, it's good that you're learning as much as you can before you choose a facility.
My first experience wasn't the greatest; they basically told me I had "separation anxiety" and that there was "nothing wrong with me." What a bunch of morons.
I had a really, truly helpful experience the second time around (aside from being suicidal, of course!). I was a patient at the Psychiatric Institute of Washington in Washington, DC. I know you are in the UK, but perhaps you can call PIW to ask if they know of the best places to receive treatment in the UK? I tell everyone I know with PTSD, who is considering hospitalization, to at least take a look at PIW.
PIW has a dedicated PTSD Ward called "The Center." It is completely PTSD and DID focused; all nurses, staff, therapists, and psychs have significant experience interacting with folks who have PTSD. As soon as you walk in, all staff emphasize that you are safe, and that no one will hurt you there. So when I woke up my first night there, shaking and in an extremely bad state, the night nurse didn't freak out. She understood what was going on.
They do everything they can to eliminate triggers; my first full day there, I started crying and shaking immediately when I noticed an otherwise harmless object in the recreation room area. The nurses had it removed immediately and I never saw it again. Group therapy is conducted in such a manner that we all got to express ourselves, but were not allowed to describe our traumas in too much detail else other folks might get triggered. There were two individual therapy sessions a week, along with a near-daily visit from the psychiatrist.
Let me emphasize that I was in an extreme state when I got there, and was an absolute handful of a patient. I was on 1:1 I think 3 times, I skipped all kinds of therapy the more I got depressed, and all manner of who knows what else.
I feel incredibly lucky to have had a therapist who highly recommended PIW; I shudder at the thought of where I might be in my life had I been sent to a general pop. ward where they didn't understand PTSD nor particularly cared to understand it.
Honest to goodness, there are times when I'm challenged by my PTSD here at home that I truly miss the hospital. The overwhelming feeling of safety, of knowing that all of your unit-mates understand exactly what you are going through, of having nurses that are trained to be sensitive to your needs (there was one bad apple who was subsequently fired), and of just being able to "let your freak flag fly" was life-preserving for me.
In order to be discharged, at least during my stay, the team (nurses, therapists, psych) had to all agree that you were not a danger to yourself or others. If they agree, you are released within 48 hrs.
Best of luck to you,
racha