Sorry Jennie, I should have made myself a bit clearer. I'm not saying you should have had the glucose tablets, just that I can see why he suggested them.
When I said I suggest food, I meant in situations such as people coming to me and telling me that they are planning to do things like run five miles every morning in order to speed up their weight loss. My response to this is always the same - if you are exercising enough that it is making a significant difference over and above your losses on Cambridge, then you need to be eating more (also if you are doing something as intense as running). I sympathize with the desire to do it, but unless the person in question is already very very fit, they're likely to cause their bodies damage with that workload on a VLCD.
I only suggest that people eat if they are planning to do a lot of exercise, or very intense exercise, though - what you have described wouldn't be enough for me to be concerned. This is also partly because I probably know more about VLCDs than your trainer does, no disrespect to him but it's just not something we get taught about as part of the standard training. The Personal Training nutritional module is excellent but it does skim over VLCDs, certainly mine did, because it only looks at them in relation to exercise, and of course, they simplify it: very low carb and calorie = advise client to eat more
Anyway, my rambling and roundabout point is this: I knew it would all be fine, I'm so glad you went, and as CD advise, take an extra pack if you need to, but mostly just stick to the plan and congratulate yourself for making such a positive step.