once the oil has soaked into the material it degrades it so it will have a shortened life
normally it takes just 350miles for a van with no spigot bearing fitted to damage the oil seal and the oil thrower that is behind it and wet the clutch to the point it's slipping, that's with a new clutch, about enough distance to get to France and break down
to change the oil seal it is advisable to remove the bellhousing as it makes it a lot easier to pull the seal and fit the new one (below flush) and you can then inspect the oil thrower and repair if necessary, it should be rigidly fitted in the case. I have replacement oil throwers made in slight oversize on the castellation edge so that if the old one is only just a bit loose and a bit worn the new one will still be an interference fit and be centred, a dadge of bearing retainer to glue in place for belt and braces, but when it's long term oil thrower failure evident after several seal replacements and a spigot bearing have not cured the leak then the case may be so damaged it needs sleeving to take a new oil thrower and for it to be correctly centred, they only have around 0.5mm radial clearance on the shaft. Paper gasket for the bellhousing may rip and want replacing when removed from box; see the drainplug magnet, change the oil.
Don't grease the guide tube just clean it the release bearing has a plastic sleeve, grease just attracts clutch dust which then becomes a grinding paste
Do lubricate the contact points of the clutch fork and the release bearing
If diesel then ensure the timing cover and cap are fitted as they keep road dirt and moisture out of the clutch and especially prevents excessive wear of the clutch fork brass bush and the resulting asymmetric wear on the fork tips
May be worth doing a lube refresh on the fork bushes, which doesn't involve melting a hole in the plastic one with a soldering iron and squirting some oil in there but I have seen dozens and dozens of bellhousings where that has been done someone must have decided it was a quick and easy way to do it back in the day