Thank you eyeinthesky, that's just the sort of guidance I was after.
If I plan via CLN and I end up having to go south of D138/D138A via, say, SND, before turning for COA, does that cause you a lot of extra coordination work or can that be accommodated relatively easily? Would that be a reasonable routing at FL70 if there were no holding at ABBOT? Via SND seems to be the usual routing when EGSC DET DVR is filed, but that seems to be with 118.82 rather than 121.22. Just trying to get a feel for how much grief such requests cause...
Are you sure you are allowed to do that? Leading Question!
I was presuming that the deviation would be initiated by the pilot.
To be honest, my main concern with that as a pilot is not the service (RIS?) offered for the short time outside CAS, but rather staying on the frequency so that I can reenter CAS when required, without having to go through London Info to coordinate the rejoining clearance while battling both weather and CAS boundaries.