reference

You MUST provide a reference. However the referee doesn't have to be your current professors (although obviously that would be the first choice).

if you select No then UCAS won't allow you to apply. It's to screen out applicants who might not be able to fill in the entire form before they get 3/4 of the way through.

so get someone else to do your reference?

http://www.ucas.com/getting/apply05/page4.html

Who should write the reference?
Your referee should know you well enough to write about you and if you are suitable for higher education. We will not accept references from family, other relatives or friends. You must have a full written reference - the name and address of the referee are not enough.

If you are at school or college, or you have only left recently, ask your headteacher, principal or an appropriate teacher or tutor to be your referee.

If you are a mature student, ask a responsible person who knows you. For example, an employer, training officer, careers adviser, a teacher on a recent relevant further education course, or a senior colleague in employment or voluntary work.

excuse me ; from the second apllication starting page " Will you be able to obtain an appropriate reference and is the referee able to provide a valid email address or telephone number by which they may be contacted?

Does this means that I've to ask to my univ professors if they can give to me a reference? I'm asking this cause am at the firt year in an foreign univ and I don't have any kind of confidence with my professors and they can't give any reference, do you think that a NO choise at this question can penalise me at the eyes of the examiners?

I´m in similar situation. I asked universities I was going to apply if they would consider my application without reference. One replied yes, so I sent my application without reference and UCAS had no problem with that.