I know this sounds extremely flippant but I will almost guarantee that it is 100 times better than you are thinking. Bear in mind that this has become a very regular (unfortunately) procedure every single day in the hospital - there were 5 scheduled the same day as me and it's the same every day.
There is some discomfort of course, mainly the shoulder pain after 48 hours caused by the CO2 gas that they inflate your abdomen with - but regular paracetemol will make that bearable.
When you come around from the op, there is no pain. You'll sleep through the first night and they will have you up and around the next day. You just lie there and examine your penis with the catheter coming out of it thinking how the hell did they get that up there LOL
Likely to be discharged later that day or the next and you learn how to walk around without catching the catheter tube - that can hurt so you learn quick.
Then it's just a case of getting used to the tube/bag and keeping it all clean and sterile. Night bags are added to handle the extra flow so that's your life until the catheter is removed after 7 days or so - that doesn't hurt either.
Almost every RARP goes according to plan - there can be complications and those people come on forums like this for advise so it makes it look like there are more than there really are. But don't worry, even they get fixed!
Just look forward to getting that cancer ridden lump out of your body - it's a pretty good feeling afterwards.
Good luck and we are all here to answer questions or concerns.