It is important for the British to communicate privacy. Try not to ask personal privacy questions without knowing each other, such as marriage, child or absence, relationship, personal financial situation, health, etc.
It is polite to eat quietly in restaurants and shops and eat all the food on your plate. If the meal is finished, place the knife and fork parallel to the plate to indicate that you have eaten. If you haven't finished eating, separate the knife and fork into eight shapes and place them on the plate.