My 2005 MY TF had a head gasket failure at 43000 miles. It did have the slightly modified elastomer gasket that was supposed to be more robust, but it still failed with the elastomer detaching from the gasket in a small area. The real change was the MLS gasket, but no MG Rover built cars had those as standard. I have seen it written somewhere that cars after late 2002 had the modified gasket, but many TFs built up to the end of production have had failures. There is also the likeleyhood that any car you buy will have had the gasket changed anyway, so age is no real indicator to what the car wil.l currently have fitted. Mine has been no problem at all in the 7 years since I had the MLS gasket and strengthened oil rail fitted when teh orignal gasket failed.
I second that got multi-layer and uprated oil rail in 2010 no problems since no coolant loss very rarely just an egg cup of coolant to replace