Thanks for the replies everyone, it is a home laptop, an acer. I have been low on space a few times as the laptop only has 2 250gb hdds, but not constantly low.
There was no option to postpone the update, the laptop had slowed right down, no mention of downloading updates until I managed to get it to load windows update check and it showed it was downloading 2 updates, I had to leave it as I couldn't do a thing with it as it was running so slow, this appears to happen when updates need to be installed, the laptop never used to be this slow, must be getting old...