Hi,
I think that your problem of glucose levels not rising quickly may have been due to the crumpet and cheese. The cheese would delay the digestion of the glucose, a crumpet with cheese is really just like a pizza.
Glucose tabs, normally work quickly; take 15 g (some tabs have only 3g each), wait 15mins (when low in the middle of the night 15 mins seems ages and I often wait less! ,) if not back in safe territoty take some more glucose, wait test again. When your levels are definitely back into non hypo territory use your slower carb. When someone has a hypo at the hospital I attend they invariably give a piece of fruit for the 'snack' as the most healthy option. The advice on one NHS site is milk, cereal bar, yoghurt, a plain biscut or piece of cake.
If you live with someone who can help you in the event of losing conciousness then Its a good idea to get a glucogen kit, to keep in the fridge just in case.
I've had some very low glucose readings in the past and have never needed it but I'm glad it's there. You could also get some glucogel which can be absorbed quickly through the gums.(though should only be used whilst concious)
As to your liver helping out, fortunately for us, in most cases, especially in adults, it will. Moreover, many of those cases in adults where it hasn't come to the resue are cases when alcohol has been involved. If the liver is breaking down alcohol it can't release glucose this can cause dangerous hypos even in non diabetics.
This is quite a good article on hypos
http://www.diabetesselfmanagement.com/articles/diabetes-basics/understanding_hypoglycemia/5/
edit: another thought is , do you often eat a low carb meal at night? If not maybe your basal is a bit high and is 'covering ' some of the carbs in your meal . What level were you at bedtime?