Thanks for the replies so far - I might well go for it. I already pay BT for a line, essentially just to connect the house alarm to the outside world so by eliminating Virgin Media I will be making better use of it + saving money too. I'm not too far from the exchange so I don't really expect any problems (famous last words!).
I shall ponder the question over the weekend...
Now, I wonder if my newly acquired Cisco routers (2nd hand/eBay) may be able to connect to Sky? Or is that against their T&Cs?