Her licence was valid, but she did not drive in accordance with its conditions. So your aunty will probably have been charged with driving otherwise than in accordance with her licence.
The magistrates' sentencing guidelines suggest a fine of half a week's net income (reduced by a third if she pleads guilty). She will also receive three penalty points, and be ordered to pay a contribution towards prosecution costs (usually about £80) and a Victim Surcharge of £15.
The commission of this offence does not invalidate her Third Party insurance.