Sanj,
Contact WV customer services on 0800 0833914. Give them all your details (telling them your after your "individually numbered Golf GT Edition 30 plaque" and if one has not been previously sent out to a former owner one will be sent to you for free. If one has been sent out before then you will not get one but they should still be able to tell you your plaque number.
If they do have one for you, IIRC you will need to send them (via email) a copy of your Reg Document showing its your car and they go from there.
I delt with a chap called Matthew Young but lots of peeps have delt with a lass called Jenny (I think).