Hi Tony,
I am the same age as you, and my diagnosis was similar to yours- Gleason 3+4, T2 (although mine was a T2C, which influenced my choices a bit). Starting PSA was just under 18
My pathway was not particularly straightforward. I had opted for RT after diagnosis for a mix of reasons- some purely subjective ( I didn't fancy the op and its attendant risks) and some a bit more objective ( I felt RT might cast its net a bit wider to deal with the measurable possibility that my cancer had begun to edge outwards).
I was started on Prostap, with a brief blast of Bicalutamide to overcome PSA flare, but this failed after a few months, so I was switched to Zoladex. It took a few months, and another blast of Bical, to get my PSA down below 4, but when they began to measure me up for the RT it became obvious that there were too many loops of bowel too close to the action. So a rethink was needed. To cut a long story short , a second and third opinion led me to the MR Linac option.
All in all, I was on HT for 2 years before treatment was finally started, but that was largely unplanned. Other than this lengthy period on HT no additional procedures were involved- no extra medication and no gold seeds. The point about the MR Linac is that the machine is recalibrated to you at every session ( so no need for tattoos and the like) and is monitored in real time during the treatment sessions. In fact one session was paused mid-flight while a bubble of gas worked its way round..... I experienced no discomfort.
You'll need to work out what works best for you, but I'd say there's no reason to be worried about the higher dose treatment. Although I chose it for the enhanced accuracy, the research I did suggested that there was no downside risk to the higher dose rate, and if anything a slight upside.
Best of luck