At long last I've found a range of snack bars (which are actually quite delicious) and suitable for an anti-Candida diet! They're made by Wallaby Australia and are available from 'Holland and Barrett'. I've tried the yoghurt fruit and nut bar (see picture) and the macadamia and cashew bar. Both really, really good :)
They probably wouldn't be suitable for someone just starting out on the diet (because of the nuts and fruit), but for those maintaining, like me, they should be fine.