I've got a vagcom licence i used until a year ago when I sold my '02 A4. I now looking at changing my car again to the Mk2 Octy vRS PD TDi which uses the canbus vagcom version, would my existing vagcom licence code be ok on the newer version of vagcom though? Would be a pain in the butt if not but was just wondering at this stage!!

No, as you need to buy a new lead with the licence built in for full CAN bus cars to work with vagcom. As you are a registered user you can get the $99 you paid off of the cost of the new lead when you buy it from Ross-Tech.

Interface Upgrades: Ross-Tech Store

Thats a bit of a bummer! Can you get 3rd party CAN cables & just use the vagcom in the basic non-registered format then?

As far as I know you can't get 3rd party CAN cables for vagcom, only the proper rosstech ones.

You can do an Outright Upgrade with Ross-Tech. This will discount your new interface/license setup by the cost you paid for the original license. The MicroCAN interface you need would sell for $149 USD instead the normal $249.

Outright Upgrade to a MicroCAN Interface: Ross-Tech Store

Not as cheap an option as the original vagcom set up now the exchange rate is in the toilet! Something to buy later on i reckon, will be a few months before I buy the car in any case as waiting for the spring to come to sell a convertible, rate might of improved by then!