MY PSA was 19 and Gleeson 4+3 and I had RT in the UK last year and no major surgery. Although I did have a TURP to help me pee as peeing was darned painfull.
I expect that the treatment for you will be the same - Mon to Fri for 6 weeks. Takes 20mins max per visit. I am lucky as can work from home so drive to the hospital, get "zapped" and back home in no time at all.
The initial visit is crucial as they measure you up so that the RT is mega accurate. I had small Tattoos on each side and front for lining up the lasers on the RT equipment. (They have since worn away.)
Skin care is essential during the treatment to stop you getting burnt. I had no side effects at all except PSA went down to 0.1 due to the RT and the 3 monthly hormone jabs. Some guys did suffer a bit with "D" - cant spell diorrea but the radiologist should explain all the possible side effects.
I admit that I am a bit surprised that this is being offered with your PSA being so low. I would have thought that a "watch and wait" strategy would have been the best option but I am no Oncologist - they are the experts.
Since last year PSA has gone back up to 10 but after bone scan and a full MRI nothing untoward so I am now in the "watch and wait" camp with monthly blood tests and visits to the oncologist. No pain at all and peeing as good as ever.
Hope that helps