Alternatively, using the example of French B&Bs to give an example of what British B&Bs might be like...
And now here's some real-world experience of Scottish B&Bs!
1 - Pub on Arran. Breakfast
at 9am.
2 - Hotel in Tarbert (Kintyre). Breakfast between 7:30 and 9:30
3 - B&B in Rothesay. Breakfast between 8:00 and 9:00
All very good breakfasts, but not exactly early. That bit of Scotland does seem to keep late hours - even in August there was still daylight at 10pm, which makes it easier.