Just to revive / update this post . . . .
We recently returned from our 3 week trip to Corsica. Beautiful place, a superb time.
My cycling has been pretty limited for a while, sadly, because of arthritis in my hands which causes a lot of problems / pain. I may do a separate post on this. I have improved things a bit by riding on larger tyres, softer at the front, and changing stem to give a more upright position (Thanks Robin Thorn for advice), but arrived pretty unfit. But the holiday was always going to be a mixture of activities, and we found several rides in the North-West of the island on reasonable gradients and enjoyed them. Long hills, but not much more so than many other parts of UK / Europe. Main problem - heat and lack of shelter / shade. Road surfaces good and vehicles generally very courteous to cyclists.
Lovely campsites - a long way and an expensive trip but well worth it.
Lewis