Do you have a contract? Legally it must be issued to an employee at a months service. Whatever notice period is detailed is what you should give (altho as another post said it is very unlikely that you would be taken to court over it, but may get a poor reference). What does it say in your contract about the end of your probabtion? does it say they will review it, when & how? Technically, if an employer fails to review your performance and they continue to let you work for them past your prabationary period, you are automatically permanent (in the eyes of the law).