Quite a few of my friends worked through university (5-15 hours per week, evenings and weekends), but that was mostly to pay for their social life. I didn't have a job during term time, but I worked full-time during the Christmas and Summer vacations, earning £2,000-£3,000 to support myself during the rest of the year - I've never had to go into an overdraft, although I seem to be in the minority on this one.
Before the top-up fees were introduced and we only paid just over £1,000 per year for tuition, the government basically said that the parents were responsible for providing the tuition fees (they can fill out income assessment forms to determine whether the goverment will contribute some of the costs).
Accomodation can usually be paid for out of our student loan, so the only thing most students need to earn money for during term time is food/clothes/alcohol etc. Now that the top-up fees have been introduced, students can get top-up loans to help with tuition, but along with the normal loans, this adds up.
At the end of the day, the students do end up funding a lot of their degree through paying back student loans - I currently have an outstanding £15,000 loan, which is increasing by about £40 every month. I won't be able to start paying this off for at least another 4 years as I will be starting my PhD in a few months time. I have a feeling I am going to end up giving the government a lot more than I borrowed by the time I've cleared the debt!
It doesn't seem fair considering that when my mum attended university in the 70's, the tuition was free and she was awarded grants for living costs which she didn't have to pay back - she basically got a free university education.