Another update:
I got my car back yesterday!!
Seems like i wasn't told the truth from the lady on the reception about a week ago!!!!
I was told by her that they had ordered, received and fitted a new mount for the gear box and that it was unsuccessful in stopping the 'noise'. they hadn't done that at all...
I had a lengthy discussion with the service manager Thursday aft, and he explained everything (i know now to just just ask for him!!). They suspected the gear box mount, but the tests they were doing indicated the chassis. This data was sent away to be looked at, they have waited for SEAT HQ to get in touch with Spain, and for Spain to come back to them etc.... Apparently this is why it took so long.
It could either be (most likely) the mount making the noise, and that is transmitting down thru the chassis or (a very slim chance) it will be a weak weld in the chassis itself.
They have now been instructed to change the mount which is on back order and should take about 2-3 weeks to arrive from Spain.
If this doesn't work then it is an issue with the chassis. This, I am told is a very simple job and not as bad as i thought.
Plus side to it all, I have my car back
and just in time as I'm off down to London next Friday which won't be embarrassing (Mitsu Colt 1.1L!!) any more.
Will post more when I know more.
P.S, saw my first 10 plate cupra on the road today, awesome car!!!