Garage Scientist Offline

I've been watching and researching the green ethos for some time and have finally got my head and backside into gear. I am very keen to take my house 'off grid' and run the entire thing using solar and wind energy. Living in the north of England I can expect little of one and much of the other, but I want to get my teeth into something small and simple to begin with. My aim is to build everything in, you guessed it, my garage. I'm planning to start by modifying my cycle machine in to a human-powered battery charger. I have researched the best batteries to buy (deep cycle to use with my solar panels when I eventually get them) and have found a particularly useful web page where someone explains how he did it. What I am having real trouble with is finding a dynamo to do the job. All research so far leaves me wanting...Am I better off going to a car mechanic and using a car alternator to generate electricity? I have exhausted the usual high street DIY stores and so-called experts. Can anyone help???