Good evening, in a "creative writing" course this question was brought up. Some of my classmates argued the plural form is "Atlas" because the word comes from Latin. Others favored "Atlases". What is the correct form in BrE and AmE ?
Assuming you're a native speaker of English or speak it as fluently as a native, always use the regular plural form for nouns except when you already know you shouldn't.
The idea that words that originate in Latin should take Latin plural forms (and likewise for Greek) is a baseless superstition inherited from neoclassical-era scholars with inferiority complexes. English is neither Latin or Greek; it has its own rules that (mostly) make sense when they're left alone and allowed to function as intended. Looking for reasons to exhume ancient grammatical rules designed for completely different languages only confuses things, and--worse--can mark the speaker as being someone who thinks he knows more than he really knows.
Any decent dictionary will tell you that the standard plural for atlas is atlases. Some dictionaries will whimsically try to tell you that atlantes is an acceptable plural for atlas, because that's what the plural would be in Greek. Would you even know what that means? If I asked you to go fetch my atlantes, would you have any idea what I'm asking for? No, you wouldn't. Then why say it that way?
I'll wager that you already know the vast majority of the irregular plural forms you will ever need. The purpose of language is to communicate, and you gain no points for confusing people with novel coinages that they won't understand instead of just following the rules you already know. Don't make things harder for yourself than you need to.