Supporting grandchildren as they take their GCSEs

As the GCSE exams go on and on and on relentlessly I thought I would like to send my two grandchildren who are currently doing them some sort of survival kit. I google d this and found that there are kits for sale on Amazon but not, in my view, very inspiring. Anyway I always intended to make up one myself. Does anyone have any ideas for contents? So far I'm thinking of sweets, chocolate, tissues, mints, soothing bath salts etc., lip balm, playing cards....