Oh deary me oh my!
I found it very confusing in Ireland -- about the use of "tea".
If I wanted just a cup of tea I learned to ask for "a cup in my hand"
The cousins gave the children an early meal (about 5 p.m.) that they called the "chidren's tea" but was what I would call dinner (meat, potato, veg etc followed by a dessert.)
When traveling thru the countryside I usually took myself to an early dinner (about 6 p.m.) and ordered from the "tea menu", again steak, potato, vegetable which is what I would have at home (USA) for main evening meal.
Then, I was once invited to "Tea" at 4 p.m.-ish by a very nice young couple I met and was served a variety of sandwiches from which to choose, both open face and regular, petit fours, a georgeous cake and of course, a variety of teas or coffee were offered. A real ceremony, all beautifully done with fabulous china, linen napkins, doilys on the plates and with a silver service and all. Phew! Now that was a "TEA!"
Is it about the same in UK?