Organic Vegetable Boxes in London

I was just wondering which are the best Organic Vegetable Boxes you can get delievered in the London area. There are some listed in the link but What's the different between organic vegetables delivered on a regular weekly basis and a one-off order for an organic veg box?

Do you get fed up with the same vegetables arriving in teh boxes or do they vary a lot?

Are box delivered vegetables that much more expensive than supermarket veg from the organic section and are the the same quality?

So many questions, but it's important to get the right delivery scheme or whatever isn't it.