Teletabby's already given the Abel & Cole link, but yeah, we're stupidly happy with them (if you do a search, there was a thread here a while back about all the different veg box schemes people were members of). We've been getting their
mixed organic box for about two years now and it's generally just about right for the two of us (if you don't pack a lunch though it might be too much, but they do smaller boxes), sometimes we have one or two things left over, but other weeks we eat everything with a day to spare - we call that "conquering the box" and my fiance gets a takeaway reward.
I really like with A&C that you can mark the stuff you hate (for us: brussel sprouts, turnips, and tomatoes) so you'll never get those but have a substitute instead, and you can mark the stuff you love (pumpkin, berries, etc etc) so you'll get given those if they're available. And if you go on holiday (or in my case, end up in hospital for weeks on end), you can temporarily cancel your box for that week with only a few days' notice. And everything's in season, organic, and never air freighted, and in general, stuff tends to be either ripe or underripe (like the persimmons we got on Monday are only now just getting soft, or bananas are often green), so I don't think I've ever had stuff go bad before we could eat it like some other people experienced with other schemes in the earlier thread.
Oh, one thing you do need to think about, though, is if there's anywhere they can actually leave the box at your place! We're lucky that we have a gate so we just give the driver the code, but they can also leave them in back gardens, in entryways, with porters, stuff like that, but not everybody has somewhere where stuff won't get nicked!