I think that by this age of car, all records will be in digital form only, so the paper service handbook/record where the second build sticker has fixed is no longer supplied.
Rumour has it that at least VW Golf, have this build sticker hidden under the plastic trim panel just inside the hatch area - how clever is that if it is true!
Other way to source this information is to ask your local SEAT dealer for a print out of CAR DATA, that document contains this information and a lot more about that specific car, even actual build date in most cases.
Edit:- CAR DATA is found within dealers workshop parts system and maybe in their workshop repair manual system. So the first place to ask for it should be the parts department.
The colour code as mentioned before should be in the boot under the carpet or in your booklet, however if you pop into your local dealership they will be able to tell you what colour you have, or alternatively post a photo of the car and I'm sure someone will be able to identify the colour for you