So you never go for lunch or have a lunch break?
Dinner is the name of the main meal of the day. Depending upon region and/or social class, it may be the second or third meal of the day.
Lunch is an abbreviation of the more formal "Lunchentach use as a word for a meal that was inserted between more substantial meals.
Tea time gets it's name from 'Afternoon tea' which is a light meal typically eaten between 3 pm and 5 pm and 'High tea' (also known as meat tea) which is an early evening meal, typically eaten between 5pm and 6pm
At school it was always Dinner time at noon and Tea time when I got home. As an adult I generally have lunch around 1pm and Dinner when I get home. However on Sundays I have a Sunday Dinner. All gouverned by when my main meal is.