Chris,
I have a detailed Checklist, split between the mechanical side of the M/home and the Habitation Area; the specifics for Paperwork, covering Passengers (Passport, Travel
Insurance, GHIC etc); and a separate Section for the Bikes (so we avoid
@GMJ mistake when he forgot to pack the bike batteries
). The Checklist is on my phone, and, as I pack each item, I place a Tick against it (we pack over the course of about a week). If you want to PM me with your mobile number, I can send you a copy of the Checklist, which you can tailor to suit your needs)
As far as the ferry crossing goes, have a look at Newhaven to Dieppe. You're over 60, so you and Mrs Chris will get a 20% Discount on both fare and a cabin (Shower, privacy and comfy bed) and the latter works out at £35-£50 net of discount. You have to book by phone because the 20% discount is funded by the Dieppe Chamber of Commerce and DFDS record the booking on a separate system, but there is an English speaking Booking Section, so very easy! Arriving in Dieppe at 0530 on the overnight crossing (invariably the cheapest fare) saves a lot of mileage, and gives bags of time to get clear of Rouen before Rush Hour. Or you can park up at the Carrefour Supermarket (about 1 mile from the Port) free of charge and head off the following day ...
Steve