“Vans RV8/RV7, the tailwheel version. Imports can be total garbage but the UK home built ones tend to be very good, even if they aren't they'll provide good economy for range and are likely to be well equipped for IFR flight, if not you can use the £50k you'll have left over to equip for IF.
All of the RVs are fast up to about 200mph, many of them can/do run on MOGAS.”
Warning!
In the UK you are not allowed to fly Vans RV8/RV7 in IMC (or any VLA or Permit machine) and none are approved for Mogas.
Rod1