Have disabled startup with windows option on TT HOME.
Yes, that file was not created when I ran F/A from the ROOT of the SD card. But the moment I copied F/A to the folder Europe_965.7280 and ran it from there instead, the dct file was successfully created!! Put the SD card back in the TT, turned it on, switched map and HEY PRESTO no error! I will test the map on the road to be 100% sure tomorrow. It also seems to let me switch ok between my 2 paid for maps.
Thanks a million BiggerDave - please assume this thread is now "solved/closed" (I'm sorry but I don't know how to mark it as so myself).