1999 1.0 micra overheat?

So I've never had a problem with my micra, my grandmother had it from new and gave it to me when it had around 70K. Its now only on 87k.

Driving home from work, in the rain, stuck in slow moving traffic (rush hour), and I notice steam coming from the bonnet. Not much, assume its rainwater. Then my coolent temp guage starts to rise so I pull over immediately, easily before it hits red.

There's no steam now, I pop the bonnet and no noticable steam. Take a look at the coolant expansion bottle and tap it to make the water level wobble to make it clearer what level its at and my finger goes straight through the bottle!! Now it has a 1cm square hole.

#1 common fault on this site for my micra is "Brittle / broken coolant overflow bottle" - but can this cause it to overheat? AA man who came out said no, but I value your opinions ;)

When the AA arrived we turned the car on and it seemed fine. No issues. Idled for a while, didnt get hot. We drove it to a garage, only 5-10 mins, but again no overheat. Temp gauge sat at half way as usual.

Any thoughts?!

the "expansion tank" is is just a reservoir basically chris, i run without one personally.
and did the fan kick in when it overheated ?

I don't really know. I pulled over and turned it off straight away - my last car (first ever car) got rod-knock after overheating and wasn't worth repairing. Hence driving the grandma's micra!

Would I definately hear the fan kick in? I am well tuned to the cars sounds, but I did have music on.

When I had turned the car off I opened the bonnet and the fan wasnt on then, and I didn't turn it back on until the AA arrived, at which time it was cooled down. Hour and a half in the rain.

just check the fan if it overheats again eh, it should kick in at about half hot on the gauge

well ive left it at a garage and will call them in the morning to see if they can fit it in, really dont want to risk driving it and making anything worse..

I will look out for it tho