Just thought my latest experience might be helpful to some newbies:
I put a toucan of Coopers Pale Ale on 3 weeks ago before I left for holidays (nothing else, just 2 cans of CPA). Pitched the yeast at 20 deg. and wrapped the fermenter in an old doona and just went away hoping for the best. I know that CPA has a mixture of lager and ale yeast, so I was hoping the lager bit would do its job when the temp. dropped.
Well, I returned last Sunday and the first thing I did (naturally) was check the SG - lo and behold it has dropped very nicely to 1010 and the temperature is/has been sitting on 12-13 deg. probably for most of the time.
So this is great news - means I can still brew my favourite beer all winter without worrying about heating!!
Nice!