I'm so so sorry to hear about your son, and hope you can find the support you need here. Yes, I'm one of the active UK members here. There is a small UK support group, but its not very active compared with this one.
My first daughter died (stillborn) at 26 weeks over two years ago now, my wonderful second daughter is now 7 months old and I love her more and more every day
I guess I am one of the success stories you wanted to hear. I felt I had a lot against me (39th birthday during my second pregnancy, some kidney damange diagnosed after the first ) but my second pregnancy had no PE, no high blood pressure, just normal throughout. There were less serious complications necessitating c section and an ante-natal stay, but really I couldn't have given a damn about any of that, just reaching full term was marvelous.
Although you are "high risk" maybe it helps to remember that what happened to you in your first pregnancy was so extreme that its really really unlikely to happen again quite as early / badly. I totally understand you feeling that you "couldn't go through that again though", and I still worry now about something happening to my second daughter to an extent that I would never have done, if it hadn't been for losing my first. I accept what happened to Alice now, but even with two years passed it is still very painful.
Let me know if I can help in any way with UK care, or anything else. I moved between my two pregnancies so have a good idea how the system works there. I'm almost certain you will be very very well looked after anywhere when you get pregnant again; my care was excellent.
Thinking of you and your son