Where you are local to me, I'm happy to give you a hand. I done quite a lot of cat 5 cable installation so have got a cable pull set, cable, stud locator, crimping tools, cable testers etc. Where the last job I did was a multi-point system in a hotel I've also got a couple boxes 305m (1000ft) of the purple 100mHz cat 5e cable, which I'm happy to bring one round for you to use as they are just sitting in my
junk room spare bedroom.
I also have experience of cutting and lifting flooring sheets and other challenging ways I've had to run cables, through ceiling coving etc. I would think being a modern build it will have timber or metal stud work that will be full of insulation material. The best way with this is normally to drill through the top plate, locate the noggin, by tapping the wall, using a stud detector or seeing how far your cable puller will go in before it hits it, then drill shallow angled holes either side and through the noggin, then feed the cable pull through to where the hole is for the plasterboard box and surface socket, then it is just a case of connecting the cable to the cable pull and pulling through. This method minimises the work required to reinstate the wall.
As somebody stated earlier no kinking of cables, all bends must be a minimum of 25mm and the absolute minimum of undoing the twisted pair as they rely on any external electrical interference being equal on both cables and therefore cancelling each other out.
When cutting flooring sheets for access, set the circular saw to the depth of the flooring sheet, make sure the circular saw does not kickback as you start the cut (as it will try to) although the slow start saws are better for this. a flooring hand saw for use by the walls and when putting the flooring sheet back screw a 2" by 1" batten underneath that goes across the joint to stop the flooring sheets flexing.
I would suggest that you use either an estate agents flooring plan or other plan to mark exactly where the cable runs are in each room, that way when you have forgotten in the future (we all do), you have it for reference for when you go to hang that new picture! You can then also pass it on to the new occupants if or when you sell the house.
Any additional networking materials you can alway get locally by opening a trade account at CMS, Hawley Lane, Farnborough. Not the cheapest, but very useful when you need bits straightway.
Where you want 4 sockets per room, where there are 4 twisted pairs in the cable, you can do 2 sockets with each cable. I've also found these useful at times to make maximum use of a cable:
http://www.cmsplc.com/structured-wiring/base-tsplitters.html