What have you been eating for breakfast? Eggs are your best bet.
Must haves:
Any meat or fish - but try and go for fattier cuts (they're usually cheaper anyway!), things like breast of lamb, belly pork, shin of beef and high fat mince.
Eggs - hard boiled they make a really good snack - it's always worth having one or two in the fridge
Butter, olive oil, lard, coconut oil
Vinegar, for salad dressings (apart from balsamic vinegar, which is too high in carbs)
Salad leaves
Shallots (instead of onions)
and a good selection of other low carb veg:
broccoli
cauliflower
celeriac
leeks
mushrooms
swede
cheese, olives and nuts make good snacks (macadamias and almonds are lower in carbs than most)
full fat yoghurt (another good breakfast alternative - look out for Total)
cream
Bacon and sausages - look out for The Black Farmer sausages as they are very tasty and also low carb
hope that helps and isn't too late!