You will need (PER HUB): new hub oil seal, 2 new bearings (get Timken - OEM), lock washer, little paper gasket and some grease.
You can get kits or look on Paddocks (you can get all the NON britpart parts from them).
Bearing is: STC4382G, Gasket is 571752, Oil seal is FTC4785G, and it's either FTC3185 OR FRC8002 and you should buy the box spanner if you don't have one - 606435 ONLY £3 - well worth having.
It's all there from page 2 or 3 in on the front axle section. You will need to look up the dates so you know which lock tab (one has a flat edge one a little lug), on a 300TDI I think you will be on the later lock washer. When I did mine I just bought both because my 90 has Disco axles and all sorts and I didn't know what age the front one was.
It might be worth jacking up the front, taking the drive flange off, taking the big nuts off and tightening the bearing up a smidge - they are probably worn but it would get your some time.
Also follow the tightening procedure properly or they will be too slack or too tight, both will cause damage.
I would also put on a new set of discs and pads; you need to strip this all down to do the discs so if you can afford it, it makes sense to do it now and save messing with the hubs again say in a years time to do the discs and saves time and a little cost long term.