Make sure you get a good plumber to do the install? I take it there won't be a crawl space? You can put access hatches in, but it's extra work and may well be no use if there's a problem elsewhere than the hatch's location. FWIW, I laid a hardwood floor in my hallway over lots of pipes and electrics - I just had to take the gamble that we won't need to access any of it any time soon.
As for fixing the boards, I used tongue tight screws. https://www.toolstation.com/reisser-torx-diamond-point-flooring-screw/p49364
I vaguely remember the Reisser ones being better than the other brands I tried. Save yourself trouble and buy a load of the correct size Torx bits as they easily get knackered as they're so small. Don't glue the boards as it'll prevent natural shrinkage and expansion.
Make sure you get a good plumber to do the install? I take it there won't be a crawl space? You can put access hatches in, but it's extra work and may well be no use if there's a problem elsewhere than the hatch's location. FWIW, I laid a hardwood floor in my hallway over lots of pipes and electrics - I just had to take the gamble that we won't need to access any of it any time soon.
As for fixing the boards, I used tongue tight screws.
https://www.toolstation.com/reisser-torx-diamond-point-flooring-screw/p49364
I vaguely remember the Reisser ones being better than the other brands I tried. Save yourself trouble and buy a load of the correct size Torx bits as they easily get knackered as they're so small. Don't glue the boards as it'll prevent natural shrinkage and expansion.