Public transport in Colombo

I know i might sound naive, but my sri lankan friend tells me that if I'm going to attend the coursres at British Council in Colombo, i have to look for acommodation in walking distance from it only. Because it's ABSOULTELY IMPOSSIBLE for european woman alone to use public transport. He doesn't give any clear reasons, just tells me to throw it out of my head. I wonder if he thinks too bad of me (i'm not fragile and not idiot) or of transport situation? Or is it really that bad?