My van won't start any more

When you turn the key, you can here the click, but then it won't turn over, I just get a loud ticking noise from the drivers side of the engine bay. Then the next time I try, the glow plug relay (the one behind the battery) chatters away and the scavenger fan starts up.
So far I've disconnected and cleaned up the battery contacts.
Disconnected things like the stereo and amp.
But to no avail.
Any body have any Ideas? I only have 5 days to fix this as I got to get to Stanstead on Thursday night.