Sarah Lloyd-Smith was a Second Year student. In her case, it was definitely a family tradition as her father was a top consultant at St.Angelas and her brother was there as well as a medical student.
From Angels Annual 1979:
Only when her three-year course was well underway did Sarah begin to have doubts about her career; but a long talk with Daddy sorted things out in her mind. Sarah is a fairly good nurse; but often lacks concentration and tends to get under the skins of the Sisters and Nursing Officers mainly because her father is one of St.Angela's bigwigs and she's therefore treated differently to the other students.
Sarah was originally played by Claire Walker (pictured left). Paul tells me that the character went off on an extended holiday with her family; but when she returned later on in the series, she was played by Kate Lock, who features in all the pictures.