Nairn's cheese oatcakes? or the ginger oatcakes that they do. They're less sugar than normal biscuits and taste ok to me.
Some people have nature valley protein bars or KIND bars, but I've not tried them, so don't know if I like them. Or, if you're feeling like baking, there's a lot of low carb, low sugar recipes on Sugarfreelondoner's website. Maybe cook a batch of them, then put most of them in the freezer so you're not tempted by them (I would have to do this, or I'd be eating a lot of cakes etc in one go).