Can some of you who live in the university accomodation and are doing a phd give a rough estimate of your cost per week. I know it depends on my lifestyle but any ball park figure will be helpful.

It depends on country, first of all. Is it UK, or USA, or Canada? Also even in the UK living expences vary a lot. Have a look at the university website where you are applying. Try section for international students. There is usually such information there.

My living costs are about £145 per week without my car included.