Call me cynical, but for the last few months, you are hard pushed to by a pack of 12 eggs online of any size.
All you have is 6 egg boxes which cost a lot more if you want 12, etc.
We shop online Tesco's but also go out to Icelands/Morrisons and Aldi's and they appear to have boxes of 12 galore, free range/etc/etc. Though there is no large Tesco near us, is this an online thing only and have you experienced this?