Good luck Chloe!
Yes you could have 2 shakes and a no carb meal, for sure
it's basically SS+ on those days & won't knock you out of Ketosis, basically the below list is good:
Allowable Food List – Sole Source + (uncooked weights)
170g Chicken or turkey breast (skinless)
180g tuna (in water not oil)
200g Quorn
225g cottage cheese, plain, reduced fat (less than 2% fat)
230g Cod, haddock, or other white fish
185g prawns pre-cooked
250g steamed tofu
2 large eggs
+ 80g of either
asparagus
broccoli
cabbage (even pickled)
cauliflower
celery
celeriac
cucumber
chinese leafy greens (including pak choi & chinese cabbage)
courgette
fennels
green peppers
leeks
lettuce, lambs lettuce, little gem, rocket,Romaine, raddicchio
kale
marrow
mushrooms
red radishes
spring onions
watercress
spinach.