I followed the advice to start with - plenty to drink but only non-caffeinated and extremely modest alcohol intake. In my case there was quite a lot of leakage, I started needing around 8 pads a day and that slowly improved over months. I think they want to discourage people trying to deal with the leaks by drinking less, partly because more concentrated urine will probably irritate the bits of the urethra that are still healing and partly because the only way your body will learn how to hold a good bladder-full of urine is giving it practice.
About six months after the operation I was getting tired of carrying my own supply of decaffeinated tea bags and experimented. Ordinary tea seemed fine for me (and I customarily drink quite a lot of tea). On the other hand caffeinated coffee quite dramatically increased leakage and the effect seemed to continue for 24 hours. I am about to try again and see if that has improved.
I also found alcoholic drinks OK, certainly up to about 5 units an evening of wine or beer. I can imagine spirits (which I don't drink myself) might be more of a problem if drunk straight.