The Avon will have C7 valves, so once you released most of the air by pressing the valve spindle, rotate it slightly so it locks to allow air to escape as you fold it up.
I'm going by how I used to put my inflatable Zodiac away (and it had a solid wood transom). Lay boat flat and fold in half (length way). Starting at the transom or stern, roll the boat tightly and pull in the sides in as you roll. You can sit on the boat as you do it to remove air.
Lastly, make a loop knot, which is basically a piece of rope with an eye knotted that you pass the other end through and pull tightly around the boat. You should be able to get in the bag and remove the rope.
Is that with or without VAT?