I noticed someone upthread saying there is no Irn Bru in England. I can happily say that in London and East Anglia there is plenty of Irn Bru in all manner of shops (not just very large supermarkets, but even small local corner shops stock it!).
Morning Rolls can also be approximated very closely with Morrisons own in house bakery rolls (this might depend on the exact store - again London and East Anglia have happily provided me with a morning roll).
Aside from the food (I would add tablet as being non-existent in England; although a large amount of fudge down here is accidentally tablet) and the house buying; education; NHS prescriptions etc. and large parts of the legal system (!) I think my very Glaswegian grandad was correct in his views on English villages....
When my parents moved south he was adamant that it would take 20 years before you got to know your neighbours in an English village. He was correct. Almost to the year. This may depend on the village - but around where they moved it's very much a 'local place for local people'.
There is - very generally - a much more private sensibility here. This might be reduced by going further North in England (I have never lived there but have visited friends a lot). Humour is certainly less 'earthy'/caustic in England. But I'm used to the West Coast and I find Edinburgh similarly humourless from when I lived there (apologies to all who are from that fine city!).
I've gone back and forth a lot between the two kingdoms. I no longer sound especially Scottish and for that reason alone I would be reluctant to return to where I grew up. I would be viewed as being wholly English, from England, which is incorrect. Sadly some of my experiences being categorised as 'English' in Scotland were pretty horrendous - whereas being Scottish in England was much more pleasant for me. That is my personal experience.
What do I miss? My family; tap water; empire biscuits; the feeling of 'home', beautiful views for the most part. What do I not miss: a certain anti-English element which definitely exists (esp on West Coast); in general the domestic architecture is more varied and regional in England...
One interesting note - I went to Northern Ireland a few years ago and it was like time travel. A lot of my West Coast Scottish childhood was present with a different accent. It was uncanny. But weirdly comforting too.
Oh finally - if you are pregnant in England be prepared to justify your entitlement to NHS services (this was very poorly handled by a London NHS trust and at a very sensitive time post-birth).