I am now a dairy free zone due to Psoriatic Arthritis - also the reason I have to lose weight. I eat no cheese, butter, yoghurt or cream. Through trial and error I have discovered I am OK with a very small amount (50ml a day max) of Skimmed Milk, which I have in my coffee in the morning.
As for snacks I have a LOT of fruit, at least 5 portions a day, popped snacks, 99 cals a bag from Morrisons, cereal bars, both the 220cal Jordan ones for after swimming and the 79 cal ones for mid morning/afternoon snacks. I was advised to try sunflower/pumpkin seeds, however I didn't find them the least bit satisfying and discovered I'd chomped through 500 cals before I'd even realised it! Eeek.
I use vitalite on my toast in the morning with Stute diabetic jam. Usually have fruit and cereal bar for lunch and Rocket and Beet Salad with meat or fish and New potatoes for tea with 300-400 cals of snacks throughout the day. I'm a natural grazer so it's better for me to snack and have little meals. Hope this helps!