It was my 55th Birthday and my Wife and I were driving to Ashford to watch 'Jurrasic World' at the cinema. We had just joined the M20 at Junction 11 and were in the centre lane passing a 'Toyota' Tractor Unit and Trailer (He was on his way to the 'Goodwood Festival of Speed') As we almost passed him i glanced behind and saw he was 'drifting' out of lane. I shouted "Watch Him!" to Tina but it was too late and he hit us just below the left, rear light cluster. This caused us to lose control and the car span out so we were broadside on to the front of the Artic who must still have been travelling at about 60 mph. He then hit us again. The second impact was incredibly violent and I thought we would both be killed. We then rolled off him, continued to spin and flew up the embankment backwards. We then smashed through a fence, took off, and flew 40 metres into a corn field. Both of us had damaged ribs caused by the impact but, apart from that we survived. The driver stopped and admitted it was his fault and that he didn't see us. He gave us both Toyota base ball caps while we were waiting for the police and ambulances.