Sorry to be an idiot but can someone tell me where the diagnostic port is? 

Just in front of the driver's right shin.  It is easier to see if you are outside and bending down or kneeling.

I have never ever managed to see one on a Skoda no matter how much I contort myself, like my rectum I know its there and can feel it, although to date have resisted plugging in an OBDII cable to download my health stats

 

It will probably happen in my lifetime and no doubt it will be me doing the connection with the doctor at the end of the internet!

just under the little pull down cubby hole on the right