This is what I and other people in my group brought on my gold
Pita bread/rye bread/potato braed, in it I put like packets of tuna cos that doesn't go off. Also got sachets of that rice you can microwave, BUT you can also eat it cold. (If that really bothers you, you could always cook it up the night before and put it in a thermos).
Brought sachets of porridge and put it in my bowl and then just had to add boiling water, also got loads and loads of cereal bars for breakfast and snacking.
For dinner I got those boil in a bag camping meals, cos they're really easy. and then pepperami sausages for a abit more
Snacks- cereal bars, dried fruit, maybe some lollies. I didn't really snack all that much though.
For training- where I was staying it was a youth hostel so we could get dinner and breakfast and pay for it, but I brought some more porridge with me for breakfast and then just bought food in a local shop for dinner (ther ewas a small kitchen). This is also good for thins like sandwiches for first day, you can buy then in the town and then store them in a fridge so they'll be fresh for day one.
Some people bought pasta, but because I did an open DofE and we didn't know each other, upside of boil in a bag is you just need water so you can all share the pot.
some people brought instanat hotchocolate which can be nice at night
hope this was helpful for people