Well.....rather than 8-12 weeks, I today received a phone call offering PSMA PET this Friday, 5 weeks and 1 day after seeing the Oncology man. I accepted!
If goes ahead (and I know can be last minute obstacles), then might be able to bring forward my next appointment with Specialist.
Still not 100% convinced I want to know (if I hadn't questioned GP's "normal" I wouldn't have!!), but will make inheritance planning etc easier, so on balance I shall proceed by the book.
Onward and downward....
Good luck all!
Dave.