I don't want to rain on your parade, but have you really considered the consequences of putting laminate in a bathroom? What if the tub overflows? What if the toilet overflows? The underlayment will get soggy and wet. You would have to seal all along the wall, tub and toilet perfectly to prevent a mess. Newer systems claim to be waterproof, but are they really? That stuff is basically particle board. Have you ever seen wet particle board? It swells and crumbles. If you go ahead with this, buy the most expensive underlayment. It will compress less under the toilet. Make a pattern out of craft paper for around the tub. Cut those pieces precisely, then fill the the gap with 100% silicone. The floor also has to move freely. If you have large area, and the toilet impedes movement, it may buckle. I would not use laminate flooring in a bathroom. A kitchen, maybe.