I've used, but Bristol area only.
https://www.thecommunityfarm.co.uk/boxscheme/login.php
I gave up in the end, good service good produce. But obviously you don't get the variety you can from a shop and I like experimenting and realy like Thai type food, so if I wanted to cook that had to buy different veg, then you end up not eating the box. They do do more mixed boxes, but what's the point when the exotic veg is sourced from abroad.
I still get a meat box from
http://www.fieldandflower.co.uk/ and can't see me ditching them.