Ray,
My boat is 13 feet with a 50 HP engine.
A couple of years ago with Me & Jacqui & 2 Grandchildren at the back ( aged 15 & 13 ) I could not get on the plane until I asked them to move forward.
In my limited experience 40 HP for a 24 foot boat would be fine for canals & the Norfolk Broads but NOT the sea on that kind of journey.
Paying for transport will be expensive but far cheaper than paying with your life!
And as for fuel . . . . . . . . . if you're not planing on cruising speed ( which you have no chance of doing ) it'll cost a fortune.
You'll be lucky to get 6 or 8mph.
You won't get on the plane and if you try you'll be wasting fuel trying to lift the boat onto the plane with no success.
Please listen to our more experienced members.
As I said . . . . My opinion.
Jim