My advice for what its worth (as a Bournemouth based PPL that has gone to the CI's on many occasions) and taking into account your preference for 'busy airspace free' routing would be to sneak down the gap between Boscombe and Solent (via the Chilbolten Radio Telescope) and route down the western edge of the Solent zone.
Obtain a clearance from Bournemouth for a zone transit and route direct to a point 6 miles west of ORTAC. This keeps you clear (to the West)of N866 and the FL35 height limitation (my preference over the sea is as high as possible with only one donkey). This routing also takes you through the narrow 1 mile gap between the airway and the south-east corner of the danger areas as you approach 50N.
Once you are in the CI zone they will tell you how they want you to route, although my experience seems to be that they provide you with a much more IFR style approach (with later descent clearances) if you enter their zone at FL60 or something like that. Sometimes if you come in via ORTAC and below N866 you can get the clearance "own navigation to Le Casquets not ABOVE 1000ft" or something similar; makes me feel uncomfortable when you can see the fishes waving at you and the whites of their eyes!!!!
If you do want to go for the Danger Areas they should be NOTAMED and Plymouth Mil will always be happy to assist in getting you through them. Bournemouth will also have details as to any operational DA's.
In truth we (I work for a aircraft maintenance company at Bournemouth) sometimes do our test flights in the inactive danger areas as it is usually pretty quiet there!!
Anyway thats my tuppence worth
Regards
N