You certainly can. Some students devote weeks of their term or a day of their week to job experience or 'placements.' If your degree does not require it, you may do work experience anytime you like.
However, we do not recommend that you substitute job experience for lectures. It's ideal to get job experience during your vacations or reading periods. However, if your schedule permits it, there is no harm in completing work experience on your days off.
You may be able to work out a deal where you come in once a week for a few weeks or months. To answer the question, sure, you may do job experience while in university, but you must manage your time well.