I understand how this works. Even with that, you can make it less bad by eating healthy, working out and losing weight. I mean do you want to make just 50 or 70+, and how do you want to feel during those years? The worst thing you can do is assume that you are helpless against your genetic issues beyond just taking medications. You can't make the problems go away but you can make a big difference in the quality of life you experience.
Low carb does not mean high fat; keto means high fat. For diabetes, eating like 50 or less carbs in a day, your full quota of protein for your body weight, and lots of nonstarchy vegetables is key. No sugar. No refined products like processed grains, flour products, prepackaged meals etc. I know it's a difficult transition in techniques and food choices at the store, but when you realize you no longer feel like mashed shit, it's more than worth the effort of say 5 minutes making an omelette with an oz of cheese and some vegetables for a low carb and filling lunch. And take a vitamin and mineral supplement. If you're low on magnesium, for example, sugar crashes at night can give you awful leg cramps and disrupt your sleep.
I don't trust the NHS to tell you everything you need to know. I've heard too much about them to think so.