We have 3 laptops and at the moment each one has a different version of our itunes library (one has a lot on, the other two newer machines only have the actual songs downloaded while on that laptip ifyswim)
I cannot get home sharing to work, presumably as these 3 laptops aren't part of a local network?
Is there anyway I can see the same library on each machine? Don't really see why I can't log into my itunes account on one laptop and see the songs I've purchased via itunes on another.
You should be able to get home sharing working, presuming all three machines are using the same router to get onto the internet they must all be on the same network. It might be worth asking another question about that and give a bit more detail about what the computers are.
What you need to do is to move the music from one machine the others that don't have it. The easiest way of doing this is to use an external hard disk drive or a big memory stick. Quite literally open up iTunes and then drag the songs you want off to the memory stick in Finder (Mac) or Windows Explorer (Windows).
Then go to the other computer and drag the music files off of the stick and into iTunes.
iTunes unfortunately doesn't work in the way we might hope where it will automatically download to each machine that is authorised on an account everything that that account has bought. The probable reason for this is that people would abuse it and use it to copy music to their friends computers.
However this does flag up something very important, if you lost that music you couldn't easily get it back off of iTunes (I think Apple might do this once out of politeness, but that's not guaranteed). So backing up the music to an external disk drive is an important thing to be doing anyway even if you only have just the one computer.