There aren't any distinct alternate words for "girl" in British English. However, there are some slang terms that are sometimes used, but they are less formal and might have different connotations. For example:
* Lass: This is a more informal and friendly term, often used in Northern England and Scotland.
* Bird: This is a slang term that can be used in some parts of Britain, but it can be considered quite informal and sometimes offensive.
* Chick: This is a slang term that is more common in American English and is not as commonly used in British English.
It's important to remember that using slang terms depends on the context and the people you are speaking to.