In my opinion, the Coopers and Munton's kits are sub-par. I don't think much of them at all.
If you can find Brewer's Best kits, those are definitely better. (Try to make sure you get a fresh kit, not one that's been on the shelf for a bit, as they have canned extract in them as well as DME. Older canned LME is not good and tastes "twangy").
I know you don't want to order anything online, but in my experience the best kits have come from big homebrew stores that crush the grains when you order the kit, with fresh bulk extract, and vacuum packed and frozen hops. They are 100 times better than any Cooper's or Munton's kit you'll ever find.