I have a 2001 1.8, nothing had been done from new, until I replaced top and bottom hose comlete with thermostat last year. This summer I replaced all the remaining coolant pipework including the metal water rail that runs behind the engine. Good job I did, there wasn't much metal left! Another few days or weeks and catastophic failure would have occured and that as they say would have been that. I noticed black scummy stuff in the coolant tank, good indication of inside of coolant hose breaking down, that's what prompted me to replace the lot.
Oh and me coolant bottle and new cap, was replaced two years ago by the sdealer I bought it from, I noticed it was crazed all over when I was inspecting it before buying. Not sure if it is an aftermarket crap part, I just noticed it is starting to craze around the filler neck, after only about 5000 mls, so guess I will be replacing it with a good part.