The overnight situation does seem to be more complicated in England. Use park4night and everyone suggests. Don't stop on laybys unless it is an emergency - that is anything that constitutes a risk to others such the side step remaining open or something flapping about or in my case, a pressing need to have an in-house pee. I will only stop for any length of time if I can get well off the road. Keep lights on and stop on the side in the direction in which you are travelling.
Type B laybys, those which have a segregation island between the rest area and the road you can stop for a good rest and picnic. Overnight is questionable, There should be a sign. Motoway services allow a stopover for a fee. I find these places usually pretty grim.
This may explain why there are more motorhome and van travellers in Europe. France is far superior. The roads are excellent (even remote country roads), there are stopovers (aires) everywhere and services for your vehicle all year round. You feel welcome driving around France. I even found new Avia services going south on the A75 first after Clermont Ferrand, with spacious showers and laundry facilties!
Scotland is great although a but chilly in winter and I have yet to test Spain, that is next month, heading to Morroco - at least that is the plan.