Went up southend last night in my 2i and while in traffic the temp gauge went half way up and little smoke/steam from engine bay but the fan didn't kick in so i pulled up when i counld let cool down then looked at the coolant level and it was below min, put some water in for the way home and it onlt went up a little, could it be the thermo stat playing up

 

If your fan didn't come on thats obviously a problem!