Your multi-cables in the attic sounds like what my electrician did for me so that I'd only be charged for one room by ntl but would have cable in all rooms. I also have sky and if you can follow my description you'll be able to have sky and ntl in all your rooms, sky will only show the one channel for reasons already explained, however its still useful.
I have tv cables from all rooms running up to the attic
I have 1 ntl cable that also runs to the attic
I have a sky cable that enter my living room in the corner the tv/dvd/vcr/digibox is in.
I only use '1 in 2 out' splitters, for some reason a booster even when not plugged in caused interference whereas to date 8 '1 in 2 out' splitters have caused no signal degradation.
Connect up all the cables using the ntl cable as the first input to the splitter and then add more splitters as required. This allows ntl to be received in all rooms including the living room. Now instead of connecting the cable from the wall socket in the living room to the tv (or vcr) connect it to the output of the sky digibox. This results in the signal being sent back up to the attic and split off to each room, now you only have to tune sky in on the tv's in the other rooms. Obviously with this setup you can't watch ntl in the living room ( I should have or maybe will send another cable down to the living room). A further spin off from this is that you can also use this setup to watch a dvd or vcr in all rooms of the house as the output from the dvd/vcr can be connected to the tv wall socket and again tuned in on the tvs in the other rooms, conveniently the dvd/vcr seems to transmit at a different signal to the digibox which means that in my bedroom I have dvd, vcr or sky digital all on their own channels as well as all the usual ntl channels.
I've possibly made this more convoluted than it needs to be, but its simple, doesn't require an electronics degree and is very convenient, oh yeah, the dvd/vcr/digibox can't be controlled by remote control unless you're in the same room as them, although I have an additional setup involving a digisender to solve this problem but get the basic setup right first before you take the next step.