Two adults, two children under 7. I quite liked the idea of Butlins in Bognor to be honest, it has everything a family needs, but it actually costs more to stay there than a package holiday abroad
I'm terrified of flying so like the idea of somewhere within ferry distance, or maybe I'll fly, who knows. Basically, somewhere abroad with the kind of family facilities Butlins offers, but not camping or caravans!
go and see your gp, tell them you are scared of flying and take pills. I used to be terrified due to an incident. but now I take something an hour before takeoff then 3 - 4 hours in if its a long flight. it doesn't zonk me out, I can still function, chat, do things but I do it. I didn't want my kids to get my fear and they haven't. good luck go for a cheap package and have fun.
Could you drive to Northern France ? Nice beaches , similar climate to Cornwall. Centerparcs, Pierre et Vacances, Eurocamp and Keycamp etc all do packages including or excluding crossings and many have facilities, not necessarily basic, and some accept Clubcard vouchers as payment