Take your time. If results do not quite meet your child’s university offers, discuss things with their school or college and, if appropriate, contact universities directly to question any adverse decisions.
Remember that UCAS’s clearing system could well provide a few gems, and the adjustment scheme could provide exciting alternatives for those who overachieved.
Schools should be able to advise on the best course of action, particularly if you need them to register your child for the Autumn retakes.