Any meat, shellfish or fish, cheese, eggs are generally where to start off.
You can cook with butter, olive oil or fats.
Lidl sell protein rolls which many people find they can tolerate even if ordinary bread spikes them.
Add loads of veges - but you need to stick to the low carb ones, lots of salad stuff, also cauliflower courgettes sweet peppers and the like - I tend to stick to under 11 percent carbs.
I avoid grains, starchy veges and sweet fruits, but frozen berries with cream are fine as a dessert, with sugar free jelly, or real custard made with cream and eggs.
There are no essential carbs, so many people happily eat around 50 gm of carbs a day and see their blood glucose in the normal range.
I have been told many times that eating a low carb diet is a dangerous fad - oddly enough by people who look drawn and tired, in need of losing a few pounds and getting a good night's sleep. As I have been doing low carb for over 40 years, I have had some people shrieking hysterically about how bad it is. but the odd thing is that I feel absolutely great, love not having to worry about my waistline, find it great to have so much energy and enthusiasm - and never need to worry about my diabetes.