Hi Richard, I can't advise on Seminal Vesicles or Lymph Nodes but your worry about your father's case could be exaggerated. Presumably he died over 20 years ago and treatment has come on since then. Also every case is different.
If you are offered an operation I think I'd be wanting to take it even if hormone and RT was needed to finish the treatment but till you've had all the tests it can't be said.
In one of your previous messages you said you were worried about telling your mother. I wouldn't tell her till things are very settled, if at all, though it's up to you. I've only told 3 people about my treatment, one my wife. I had 2 days in hospital 12 months ago and only my wife knew, although I am retired.