Organic Produce

I was recently referred to this site and have found it very interesting and informative. I have revisited several times already to take advice, as I am now in the process of clearing out and restocking my kitchen. Currently, I am sourcing what organic produce I can from Tescos. How reliable is their organic range and is it certifiable? Could you recommend anywhere in the Chester area I could source decent, natural food? Thanks for a fantastic site.  The traffic light rating system is especially useful to me. Neil