It depends... if you're as lazy as me you can make it so thats its next to no work (at least as far as the 3rd year) and just about get away with it! Though I know some people on my course who voluntarily work nights and stuff for no good reason... theyre mad i tell you!
The only student nurses Ive bumped into on the wards seem really shy and hide behind the senior nurses all the time! Mind you, with some of the consultants around these hospitals I think you need a "matron" style nurse around to keep them in check! Theres one consultant who seems to insist on calling every medical student either "you there" or just "boy" depending on what mood hes in! Its very amusing though!