Don't forget that if you are having separate boxes rather than sharing 1 or 2 boxes between rooms that you will need phone points for each box.
Whilst they are running the coax to the points, put in 2 x CAT5 cables to each point and terminate into a double network faceplate and get secondary telephone to RJ45 jacks to plug in phones or sky STB's.
Run all the CAT5 cables to a central point and terminate into a patch panel.
You can then use the CAT5 cables for telephone, computer, video etc.
I would run all your coax to the same point thus creating a distrubition closet.
Have a separate 20A radial run for the closet from the consumer unit.
Are you really thinking of having 6 to 8 boxes?
With the sky world package at around £46 and an extra 7 boxes thats £116 per month
and don't forget any HD subs at £10 extra PER BOX on top of multiroom.
How many people are in the house? You may be better sharing 1 or 2 boxes between multiple rooms with magic eyes to change channels from the other rooms. (Then your recorded Sky+ content is not tied to 1 TV)
Have a search for loftbox and you might get a better idea