If the danger areas are cold (very likely on a bank holiday) I'd go dct ORIST dct and fly higher. ORIST is on the Eastern edge of Q41 near ORTAC.
Get a radar service from Bournemouth and transfer to Jersey zone about 15 miles NE of ORIST. They'll clear you into the zone and give you an altitude and pass you on to Guernsey. You can get the Guernsey ATIS from GUR VOR a good 50 miles out.
The GAR form sent to Customs and Special Branch 12 hours before you go will do the formalities, I should imagine the ops folk at Shoreham would deal with that for you if you give them the form.
Don't forget to file a flight plan with ETA for zone boundary and request for SVFR clearance in box 18 assumin this is a VFR flight.