8 or 16v?
if 8v get the mk3 rubber rocker cover gasket and the associated studs. do a search the part number is on here somewhere and will cost you about £11 from VW. you might as well replace this as the sh!tty cork one will probably split when you take the rocker cover off.
rocker cover gasket
head gasket
headbolts
oil and filter
coolant
you might also need the odd nut/stud for the downpipe to manifold as they are often buggered by the time you get them off.
tool wise,
star bit for headbolts
10,13,15,17mm spanners and sockets
torque wrench
wd40 type spray
err thats all i can think of, you probably will end up with a bunch of extra tools but thats what you really need.