Are 'minha mãe...' and 'a minha mãe...' exactly the same thing or is there some subtle variation?
No, they're the same ^^
by the way is it gramatically correct to use both versions? as it Italian you say "la mia madre", in Spanish you never use an article before "mi madre". so how is it in Portuguese?
Haven't you seen “a minha mãe”? Mainly in Brazil, we use an article before.
Can't we distinguish between English and British?
English = inglesa / British = britânica
How would one say, "My father is English?"
(O) meu pai é inglês
O meu pai é inglês
... and my grand mother is Latin, says American English