Yes, you need:
1.Silent Coat 2mm damping mat - £14.99 for ten sheets (enough for both doors with plenty to spare):
http://www.ebay.co.uk/itm/Silent-Co...Proofing-Damping-Mat-/161282941044?nav=SEARCH
You stick this product on the inside of the door on anything that's metal. It stops the vibrations that cause 90% of rattles. I covered 70% of the surface but 50% coverage is fine for optimal results. You will need a pair of decent scissors to cut it but be careful not to run your finger across the edge because it gets sharp.
You can see this product in action here:
https://youtu.be/h1P4L7TwV9Q
2. Silent Coat Sound Absorber 15 - £44.99 for 4 large sheets (absolutely loads, plenty to do both rear doors as well if you have them or the wheel arches in the boot):
http://www.ebay.co.uk/itm/Silent-Co...Deadening-Foam-Tiles-/161288391178?nav=SEARCH
This gets stuck onto the back of the door cards. I covered 90% of the doorcard and the more the better with this stuff.
These two products work together - the 2mm stuff stops vibrations and the 15mm foam kills exterior noise dead. Combined they eradicate rattles completely.
You will also need a pack of door clips, as you will end up breaking some of them when removing the door card. These are the clips you need and at £3.35 for 10, I recommend getting two packs:
http://www.ebay.co.uk/itm/VW-T5-DOO...INTERIOR-TRANSPORTER-/400277527904?nav=SEARCH