intermittent abs warning peugeot 307?

Peugeot 307 1.9hdi ,abs light on dashboard comes on with a beep sound and can stay on .at the same time the centre information lcd bar will advice of a abs fault then go out .But sometimes i can start the car and get no warning about any fault.Annoyingly my daughter needs the car in 2 days time for her driving test. regards,desperate ken.