For medicine, the work experience you do isn't so much what you do but what you get from it. It's very important to reflect on what you learnt and how your outlook on things changed as a result of the work experience. Many people have links to people/places to get lots of experience but unis won't be impressed by this. They'd rather you reflected and learnt a lot from your part time work behind the bar than sat in an operating theatre for a week but achieved nothing!