about contract terms

Hi! Anyone who knows the different contract term/period when working in the U.K.? For example if the job offer's contract term is 1 or 2 years, does it mean after those years, the contract is ended and the nurse will go back to the country of origin? I'm confused whether working in the U.K. is a temporary one or would it mean, you'll be a permanent resident eventually. Please kindly tell me because I'm having a hard time researching for the real answers. Thank you so much.