Hi TL,
I am so sorry that you are facing this horrible choice. Having been there two years ago, I know just how much this will scramble your mind and both decisions will seem like options you don't want to take. You have done the right thing by coming on here and asking for other people's experience.
I can only speak from my experience and I had to go down the surgery route. I had a condition called Ulcerative Colitis and this prevented me from having radiotherapy. So the first tip is to make sure you have informed your treatment team of any conditions you might have. My team were not aware of the Colitis until I told them!
Assuming you don't have any other medical conditions then the things to know about the surgery route is:
You need to know if your operation will be nerve sparing? In some cases the removal of the prostate will require the removal of the nerves around the prostate. If these are removed then you are 95% certain to never have a natural erection again. My operation was non-nerve sparing and I haven't had an erection ever since and have come to terms with that being my fate.
My operation left me incontinent for 5 months. The NHS provided pads that I had to wear for those 5 months. I still have a minor weakness that means a sneeze or cough may end in a tiny leak. When I over exercise or have a bad cold there is a higher risk of leaks, but nothing that has been so bad that people could see anything.
The operation will shorten your penis by 1 to 2 inches. As I don't get erections this is not a huge problem for me. I do use a vacuum pump (provided free on NHS) and a cock ring does make it possible to have penetrative sex but this is not perfect as it can be uncomfortable and there can be issues where the penis bends around the ring (I don't have this, but have read it from others in the same boat).
Obviously the above is a lot to handle and I needed help. I had cognitive behaviour therapy from November 2024 to January 2025, which helped me to come to terms with the above. I would encourage you to see your GP and get a referral, but be aware it is a long waiting list.
Before the Colitis set my treatment path, I did have the same choice as you. I was going to choose the surgery and my main motivation was I wanted the cancer out of me. After the operation they do a full examination of your prostate and they informed me that the original diagnosis of Gleason 4+3 had changed to Gleason 4+4, as they had found that the tumour had breached the prostate and my risk of spread was now higher. I am glad I had the surgery for this reason as I am now clear where I stand.
If you have any more questions on the surgery please ask. I am sure someone from the radiotherapy route will soon respond. I wish you all the best with this choice and wish you all the success in the world with whatever route you choose.