Flybymike
At the moment in the UK aircraft should not be flown with fuel that is containing alcohols (Methanol/Eythanol) as this can contain water increases the chance of carb ice forming.
Aviation Mogas is free of alcohol.
As said above the Rotax can use fuel that has some alcohol in it but it is not yet approved in the UK. I know of one Rotax supplier that will sell you a fuel testing kit that you can use to check for alcohol in MOGAS to tell you if it is fit to put in your aircraft.