Thanks to everybody for the advice, which is much appreciated.
I did consider microlights, etc., but I suspect I'm too tall, to wide, and too heavy. I'm 6'5'' tall, 3 feet wide, and weight about 19st
In a Cessna 172, with the seat wound right down and pushed right back, I can just about get in, with about an inch clearance over my head. Quite honestly, I would be happy to fly anything. But I've got to be able to fit in it.