Hi QDM,
If I were you I'd chat with Plymouth Mil from Devon to PB to check the status of the DA's south of Portland, [and Lyme Bay if you plan to cross that] and if inactive, head stright from PB to ORTAC, chatting to London Info on the way over. Near the zone you contact Jersey Zone for your entry clearance [assuming you're entering the zone]. If you fancy a stop in the CI, try Alderney, there is a great curry house there, plus you get your fuel draw back, and duty free booze as a bonus. Landing is about 8GBP with fuel I believe [and its just a hop to Cherbourg].
I haven't got a map here, this is all from memory, so apologies if I'm talking out of my arse
In my experience, its actually a piece of cake flying around the CI's. If routing to Alderney, Jersey zone will give you entry clearance, and sqwark, then will hand you off to Gurnsey approach and finally Alderney tower when you're in sight.
Cheers
EA