As Raywood said, the services at Gretna have a small supposedly caravan only area. From memory I think it holds about 10 caravans but ,to be honest, I stopped using it some years ago as I found I could not depend on getting parked there usually because of transit vans and private cars using it. Perhaps they have tightened up on that though. Can be a busy place as it caters for both Norh and South Traffic.
The ones furthe north than that I don't usually use as they are fairly close to home.
Next service area up from Gretna is Annandale, a relatively new area, again caters for both North and South bound Traffic. Never been in there.
Abbington is next up, again serves Traffic going in both directions. Stopped there once many years back, someone needing the toilet I think although it's only half an hour from home. Seem to recall signage for caravan parking although we were certainly parked next to HGVs, whether they were in the wrong bit or I was I couldn't say now.
There is, or at least was, a service area at Happendon, between junctions 11 and 12. Stopped there once when travelling solo, plenty of parking but certainly at that time the term service area was an exaggeration. More of a filling station, but certainly was plenty of parking area. Again serves north and south bound.
Next is Hamilton, never used it but pass it often and it always seems busy, caravans in with the HGVs. It serves north bound only.