Hi
@tuanteo welcome. Your profile is a little sparse in detail. It is not clear if you are Type 1, 2, LADA. In general if you are an omnivore, then go for any meat, fish, shell fish of which I would recommend the quality that fits your budget (be wary of supermarkets, some of which add sugar to meat). High meat content sausages, bacon and the like.
If you like / tolerate dairy, this is a good option.
Any fruit ending in berry
A few nuts, apart from cashews (25% carb) and peanuts (ASDA do a brand at 4% carbs per 100 grams though, so this is choice)
As for veg, courgettes, broccoli, asparagus, cauliflower, toms, mushrooms, greens.
Drinks, tea, coffee, water (sparkling is good), fruit teas.
If you are Vegan or Vegetarian, just say so and others will help.