This is the problem i have encountered from day one and the thing that imitially led me to believe TWRP was corrupted (can now see it's not.) TWRP was refusing to mount any storgae but now have the same on cwm.
If I could just simply mount then I would have downloaded a different rom long ago, so while I really appreciate the help and advice, that option is now open to us.
The good news is we now know TWRP is probably not corrupted :-)
I could try adb pushing a different rom, is there a tutorial on here anywhere?
By the way, the error in cwm is: "error, cannot mount sd card."