I say tea usually (northerner) though I say dinner too. Which means sometimes my meals go: Breakfast, Dinner, Dinner My best friend is a southerner and she was talking about having some tea once and I had to ask her if she meant "drinking tea" or "eating tea".
I'd say it was as much a class thing as a north-south thing. I'm a southerner and say dinner, but most of my family, all of whom grew up in London, say tea.
I used to say say "tea" but after moving south for several years and causing utter confusion with my housemates, friends etc. I was converted to the term of breakfast, lunch and dinner and it's stuck.