Im not 100% due to not knowing the nutritional info of the gravy if its counted into your daily carb allowance along with the veg then its all hunkey dory.
Someone more carb savy will be along to tell you more than me soon enough
I saw someone on here recommend stock cubes called "just Boullion". I make that up and add a bit of fresh cream. It has less carbs than bisto, but I can't remember the exact count at the moment.