Oh Sally, sorry to hear his tum's off again. Cheddar is a common culprit, but it could just be that he hasn't managed to rebalance his gut flora since his reaction to the initial food and once he's had some probiotics he'll be able to eat more things again.
Pip seems to be able to handle things so much better now. He's currently having a mix of roast chicken, Fish4Dogs Star Training Treats and Canan kibble for training and meals and supplements that nicely with random bits of mud, grass, leaves, sticks and anything else he can get down faster than I can say 'leave'.
Sweetkitty, I did a nutrition module as part of my canine studies course and every single person on the course immediately changed their dog's diet when they realised what they were feeding them.
With the higher quality foods you may find that she won't need to eat anywhere near as much as cheaper foods to get the same amount of energy and nutrition. The amount of food ours ate on Canagan compared to James Wellbeloved was considerably less, despite JW being considered a 'good brand'.
Jax, I know it's much cheaper on there. £1.90 a packet if you buy the 20 bag box, but I'm having to wait to buy that many in bulk, as last month was a tad expensive round here. I'm just did an order from Vet UK because I was ordering Canikur anyway and it was easier than having multiple deliveries.
Happy, it's not as bad in a moving car, if you have a window open or air conditioning she'll be fine. It's when you leave a dog in a stationary vehicle on a sunny day that it becomes dangerous, as there's no air circulation and the temperature inside the car can rise incredibly fast.