Dr 400-180
The Robin DR400-180 seems to fit the mission profile perfectly.
With 4 seats filled it will get to the other end of France/Nothern Spain from Oxfordshire with only one stop, or if the suplimentry fuel tank is fitted it will do the trip non-stop with two pepole and bags.
The Robin will do this from a runway far shorter than any of the fixed pitch offerings from the USA and 10 to 15 Kt faster in the cruise.
The maintenance is at fixed gear and fixed pitch prop prices, added to this the Robin structural repair manual is writen in such a way that you will never get into the situation that pilot DAR describes above.
Added to this the Robin is much more fun to fly and you can keep a far better lookout with those big windows.
The smaller American retractables dont offer a big enough speed and payload advantage to be worth the extra cost to be worth moving to, It requires a jump to the upper end of the SEP range to get a big enough jump in performance above the Robin to be worth doing.