Having said that, your choice of TG is one of the better airlines for NOT having a YQ fuel surcharge. A redemption on most of their routes from Europe costs about 27 Euro (MXP) to 140 Euro (LHR of course) in local taxes. I did two of these last year and chose Thai for the reason that there were no fuel surcharges. EDIT: Since then, they seem to have added a 64 Euro charge on every flight to Europe, so you're looking at around 100 to 150 Euro going eastbound and around 85 Euro westbound. All figures from ITAMatrix.

The figures vary a lot by direction too. For example, Air Inida currently has large (~190 Euro) YQ on Europe-DEL-BKK but nothing on the return. A BKK-DEL-CDG redemption can be had for 20 Euro total tax.