After 1 January 2013 l believe l will not be able to buy petrol and will have to look for an alternative Any recommendations which one will be the best from E20,Gasahol 91 or 95. Many thanks

How can anyone answer that without knowing the make and model of your car? Your owner's manual will tell you, there may be a sticker on the inside of the hinged cover over the fuel cap, your car's dealership will be able to give you an answer.

If your car can accept E20 it will be clearly marked, there is then some scope for debate about whether E20 (80% benzine/20% ethanol) is value for money: it is only 1 baht per litre less than E10 (gasohol 91 and 95 are 10% ethanol) yet you're getting 11% less benzine so you can expect slightly decreased fuel economy because although ethanol has a higher octane rating your car's compression ratio is set up for gasoline and can't take advantage of this. This varies depending on make and model.

I'm guessing the OP's car is older.

The mrs said the scrapping of unleaded has been put off last I heard.

The government are too thick to workout whose votes they want to buy so it has changed. I'll have to check the latest on it.