In British slang, "good morning" can be expressed in various ways depending on the region and the context. Here are a few examples:
"Morning!" - This is a common and casual way to greet someone in the morning.
"'Ello!" - A shortened form of "hello," commonly used in the morning as well.
"Mornin' gov'nor/guv!" - This is a more old-fashioned and playful way to say "good morning."
"Top of the morning to ya!" - A phrase that has Irish origins but is sometimes used in British slang to greet someone in the morning.
It's worth noting that slang can vary greatly across different regions of the UK, and what may be common in one area might not be as prevalent in another. Always pay attention to the context and the people you're speaking to when using slang terms.