Simon, I would check your radiator.  If it is copper, then you could try to
solder it as a temporary repair.  If it is aluminum core (probably) then I
don't think it can be repaired at all.  The other thing to consider is that
if it has a corroded hole in it, that this is just the weakest spot in the
radiator, not the only bad spot.  So if you fix this spot another will
probably soon spring a leak.  Because the radiator for the Vanagon has
plastic sides, none of my local radiator places here in the US will even
attempt to recore it.  I know that Australian mechs and shops specialize in
keeping older cars alive and so maybe they would at least attempt a recore
for you (my friend is a missionary there and he told us about the 100% tax on
imported vehicles, yikes!).

If not then I would suggest buying a new radiator from myself or another
vendor.  I have these for $195 and I could ship this radiator to you via USPS
Air Mail.  I hope this helps you.

Thanks,
Ken Wilford
John 3:16
http://www.vanagain.com
Phone: (856)-327-4936
Fax: (856)-327-2242