Lisa,
At the moment, if you have just passed your driving test and you are only 21 years old, you will not be able to get temporary insurance. All insurance companies require that you have a
minimum of 1 year's driving experience before you can buy short term policies.
You can however get 1 month car insurance as a minimum though with
eCar Pay As You Go Insurance. Other than that, no insurers are likely to take you onboard.