Searching for a Survey Model on Why People Buy at Supermarkets

Hi,

I have been trying to start a root grass project to gather a community of people in Ealing, a London area, interested in actively adopting sustainable behaviour. One of the ideas I have got in mind is to contact the London Farmer's market organisation that promotes local organic food markets to organise a survey. When we need to know better is what drives people into the supermarket instead of buying at the local market just in front of it. Is it just a matter of price? Are they aware about issues such as food miles, supplier exploitation, packaging, etc? From the results of this survey I would like to understand better what issues need to be tackled first in our area, and build a workgroup around those. Now, I have never written and processed a survey myself, so I thought this was the best arena where to find some ideas. Could you help me in constructing such a survey? Survey templates, case studies, tips on what to keep in mind when investigating this issue, similar works,etc I apologise if this issue was already discussed previously, I try to read all the emails in this mailing list but I don't always manage.

Thanks a lot in advance,
Nicoletta