The release bearing.. though I think it's also likely to involve the sprung clutch plate fingers.
Over time the fingers get wear on the tips where the release bearing presses against them. As the bearing wears through the fingers they distort slightly and that makes a rattle. Some of them might even drop off as the bearing wears through them.
You'll need to get the clutch changed and fit a new release bearing (though these usually come with the clutch. Check that you have a new bearing, especially if you go for a budget brand clutch.. just in case it doesn't).
If you have a concentric slave cylinder inside the clutch housing (I think 1.6 is a "piston" style cylinder outside the gearbox though) also change that at the same time, since the expense/effort is getting the gearbox off to change the clutch, not a few quid more for a new slave cylinder).
As it is, the beast could soldier on for months... but if enough of the fingers let go altogether, the bearing will push through the fingers and you'll have a terminal clutch failure/breakdown... and winter is coming.
Ralf S.