1) Which is correct:
A) At weekends, afternoon tea is a special occasion.
B) At weekends, the afternoon tea is a special occasion.
2) Should I say "at the weekends"?
1) Which is correct:
A) At weekends, afternoon tea is a special occasion.
B) At weekends, the afternoon tea is a special occasion.
2) Should I say "at the weekends"?
1) "At weekends, afternoon tea is a special occasion."
You are talking about "afternoon tea" in general, so no "the" is needed.
2) Meanwhile, both "at weekends" and "at the weekend" are acceptable in British English. In American English, it would be "on weekends" and "on the weekend(s)."
Source: https://english.stackexchange.com/questions/75466/at-on-the-weekends