Just spoken to the ticket office and upgrading to platinum is only suitable for the full adult tickets.
If you are young or old, then no point in doing anything other than gold! Guarantees you priority for away tickets, but not automatic.
The 1330 points for platinum is slightly mis-leading.
I guess this is actually 1100 points plus 23x10 points for the aways. I guess that cup games will be added also when occurring.