@flyingfemme,
If they're starting Ground School then most things are provided at that point. Perhaps with the exception of one item of stationary which you could use with the CRP-5 flight computer. Which are 0.4mm fine point pens, such as those made by Stabilo. For revision purposes one of those small whiteboards which you can pickup in TESCO or many stationary stores and a set of pens may come in handy for jotting quick calculations etc on! See here:
For the flying stage, perhaps a pair of non-polarised sun glasses or at least some money towards them may make a nice gift. Headsets etc are typically provided too.