well i found it quite helpful actually. i'm currently studying at university here and at first i tried to learn from my classmates. thing is that even though they can teach you some useful expressions they cannot explain the grammar to you ('it's just the way we say it') .. which makes it difficult to construct any sentences of your own.
at HKLLC they really stress the grammar part which makes it easier to 'fill the gaps' with additional vocab. found that quite useful.
i do not use cantonese in conversations with classmates because i'm simply not good enough, but i can usually guess what they're talking about. i know enough to get around, order food, ask directions stuff like that (even on mainland, which i think is the ultimate test).
final thing which works slightly in my advantage that i'm asian (i dunno about your relative), so people here think i'm local and will automatically speak cantonese to me, therefore i am forced to speak cantonese as well

.. else i would probably choose the easy way and speak english instead (and never learn cantonese)