Formal:
* Good morning/afternoon/evening: This is the most polite and common way to greet someone, especially if you don't know them well.
* How do you do? This is a very formal greeting, used mainly in introductions.
Informal:
* Hello: This is the most neutral and widely used greeting.
* Hi: This is informal and widely used, particularly among friends and peers.
* Good day: This is a more traditional greeting, often used in rural areas or by older people.
* Hiya: This is a very informal and friendly greeting, often used in the north of England.
* Alright? This is a casual and friendly greeting, often used among friends or peers, and is often used as a shortened form of "Are you alright?".
* Right? This is a very casual and informal greeting, used mostly by young people.
Other options:
* Morning! This is a short and informal greeting used in the morning.
* Afternoon! This is a short and informal greeting used in the afternoon.
* Evening! This is a short and informal greeting used in the evening.
Remember that the best way to greet someone in British English is to pay attention to the context and who you're talking to.