I use
Breakfast
Elevenses (usually savoury snack between 10.45-11.15)
Dinner/lunch (between 12-2. I use both terms, I've lived in the north and south - but prefer dinner)
Threeses (usually sweet snack between 2.45-3.15)
Tea (evening meal, between 6-9)
Supper (small snack shortly before bed)