Personally i shop at the greengrocers...v. cheap. Also have an allotment...defo the best way for being forced to be inventive with truck loads of veg....50 ways to cook with courgettes anyone??
Dont see the environmental argument for veg boxes...if you are getting pineapples, sweet potato and any other vaguely exotic fruit/veg then surely you dont think these are grown in blighty!!
Fairtrade...lots of veg grown in this country using low paid eastern european labour living onsite in grim conditions??
As for organic/non organic then speaking as someone who works for the pesticide regulator i would avoid any type of baby leaf lettuce and leaves and remove outer leaves from whole lettuce. But most other stuff i wouldnt worry about...but wash everything before use. Organic doesnt necessarily mean no pesticides used