I've spent plenty BofE notes in Scotland but I rarely see a Scottish note down here.
Things might have changed, but years ago I was on my way back from a temporary work placement in NE Scotland and had to stop for fuel at a motorway service area* south of the border.
I only had Scottish notes so asked if they were acceptable before purchase and was told they were allowed to take them but not give them in change.
What the state of play is these days, I don't know, but have a feeling that you still might have some difficulty in getting them accepted in England.
Plastic, of course, solves these problems.
*Never a good idea as fuel is always ruinously expensive at these places, but needs must...