AuntieMaggie Can you take a coolbag with you, and pack a bag with stuff like hard boiled eggs, some packs of ham/cooked meats/smoked salmon? If you have a minibar in your room you could keep them in there overnight.
Also, if you're driving, check out the service stations that you will pass en route - lots of them have M&S food outlets now, so you could buy stuff from there - salad stuff, or cheese, olives, etc.
Hopefully, being in hotels, you can at least have a cooked, low carb breakfast every morning, which should sustain you till lunchtime.
Happy birthday horrorcayn 
Piffle sounds like it's going really well for you!
Lavender - are you eating plenty of fat and drinking plenty of water, along with green veg/salad? If you're still suffering, and don't want to buy laxatives, the other thing to try is Thornton's sugar-free/diabetic chocolate/toffee. Just go easy with it, as it is very, very potent!