Burgen do one that is soya and linseed and lower in carbs than other loaves. There's a low carb bread called Livlife I believe that Waitrose sell that others use. Maybe fill one slice with lettuce , slice of ham, cheese and just a tsp pickle.
I'd recommend getting a meter. Home Health do one called the SD codefree that lots of us on here use as strips are lot cheaper than other makes. Although we are told by NHS not to test and to eat carbs with every meal, I think you'll find that doing the opposite is the way to good control.
It's a lot to take in at first. I can never work out how to link to the recommended guidelines on here, but I'm sure
@Bluetit1802 ( hope she doesn't mind me tagging her) will post them on here as she us very good at that sort of thing.