@notepadplusplus - To be honest, in this weather, the lack of refrigeration wouldn't concern me. I'd just put whatever I fancied into a clip-lock box in the boot.
For a 6 hour journey, I'd not want a big full meal, but I'd likely want something decent to eat, rather than nibbles. There's nothing worse than boredom for generating (false) hunger pangs.
For me, that might be a couple of chicken thighs or a chicken portion, with some salad and cheese. It could be decent cooked sausages, a cheese box, hard boiled eggs, gammon, cold cooked salmon, or smoked salmon, but the beauty of the likes of chicken thighs or sausages is wrapped in foil, they can become finger food, negating the need for cutlery.
We bought a couple of these about 18 months ago. They're ace. So often you see claims of keeping drinks hot or cold for x many hours and being disappointed? These don't, in fact, if you don't want to be hanging around waiting for it to be cool, be mindful how hot you make your drink.
If I am going to the office all day, I tend to make a drink and load the flask before I leave home, then leave it in the car all day, in whatever weather, then I have a drink to sip in traffic jams on the way home. It's just plain fab!
https://www.amazon.co.uk/gp/product/B0148QIJO0/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
