In case anyone still wanted this information, this worked like a charm (remove spaces, I have insufficient posts for external linking):
http :// hotodi. com/ install-google-play-on-cobys-jelly-bean-tablets/
Again, my tablet hasn't been rooted and it now runs Jelly Bean and the Play Store. Happy days
It is only version 3.7.11 of the store, but after trying to install a newer version from the above link (which failed to install), I'm just going to wait and see if it updates itself over time.
I'm happy at the moment