I've noticed recently that more and more people are learning Mandarin here in UK. As a Mandarin speaker myself, I think it's an ambitious thing to take on, but if you fancy it, here are some useful resources. In addition to the actual language, familiarity with Chinese idioms and proverbs is very useful and comes up in everyday conversation. And if you come across a character you're not familiar with, you can try this site, which cleverly converts it to a phonetic form for you.
As a side note. Every Chinese person knows how to play Mahjong. They seem to know this from birth. So if you're serious about mixing with the locals next time you're in China/Taiwan, it might be worth checking it out... I wouldn't play for money, but it is quite fun!