As Ali said, it's all most of us have. Low GI, and carbs 12 grams per slice rather than 18 or more. Not great in my view taste wise, but works so I eat it. Sainsburys, tescos Iceland and others stock it.
I can't tolerate even a quarter of a slice of regular bread, but I can manage half of a slice of Burgen. To be honest, I now make my own as the bread I make is very low carb so I can at least make some toast or a sandwich, impossible with my tolerance levels, even with Burgen.