I disagree with the nurses' approach. The whole POINT of basal/bolus is to eat what you want, when you want, and take an appropriate level of insulin.
The general idea is that you give yourself 1 unit of Rapid for every x grams of carbohydrate, for a type 1 diabetic it's typically something like 8-15g. Many people find that the ratio is different in the morning, midday and evening (due to your body clock). So you may find you need 1unit : 12g for breakfast, 1unit : 10g for lunch, etc.
NovoRapid lasts about 4 hours, so you generally figure out whether your dosage was too high or low by what your readings are like about 4 hours later (of course this is thrown off if you have another meal in that period, maybe that is what the nurses are trying to avoid, but IMO it's not a big deal, you'll figure things out).
Levemir is trickier to work out, the idea is that if your sugars tend to go low or high when you haven't got food or NovoRapid in you you need to adjust the Levemir.
Good luck!