As an ex ATCO from Jersey, I can tell you that Jersey will only accept aircraft Special VFR to land at Channel Island airports, if the vis is 3000m or greater and the cloud base 600 ft or more. These are local rules and are in the Jersey ANO. If you are transitting the Zone as long as you can remain VFR(clear of cloud) you are normally accepted but expect to be cleared at FL55 direct Skery to Dinard. They assume that you hold a valid IMC rating if not the limits on viz are 8kms.
The Zones around Cap de la Hague and Flamanville are still active so keep well clear otherwise you might be formated on by a FAF Mirage! these can fly remakably slow as they check your registration(as a local pilot found out recently)
Enjoy your trip