How to Speak English Naturally

Is this kind of regional British slang appropriate for your everyday use? I wonder. It depends on the situation you're in. If you're speaking with native speakers, it's useful to know all this stuff because it's going to come up,. But if you're learning English to be used with other foreigners, with non native speakers of English, it's not necessarily going to be a good idea to start throwing in these slang words and expressions.