There should be a clause in your employment agreement which states how much notice you will be given if you are dismissed during your trial. In general this means that if the employer wants you to leave straight away (rather than working through your notice period), then they must pay you for the notice period.
The notice period for your trial period can be different from the notice period once you are finished the trial period, as long as the notice period for the trial is specified in the employment agreement. If the notice is not specified for the trial then your employer should adhere to the notice period in the employment contract.
If you are confused about your notice period, or have been dismissed on the spot without any notice you can call us free to find out if there is a case for unfair dismissal.