Had an accident, who's fault is it? Who gets the claim?

I was on a two way lane on the left side. 10m ahead was a traffic light which was red so i temporarily stopped at a bus stop in my lane for say 5-10 seconds to drop a passenger. I then moved straight forward, not left or right because the bus stop was on the left lane. As i went forward in say 0-6 mph I see a parcel force van come into my left lane from his right lane while indicating. So i immediately stop but because there was sufficent gap between the van and me the van coming into my lane hits my driver side wing arch and i make contact with the middle of his van on the passenger side. Since, its supposed to be my lane, and since he's changing into my lane should he not be 100% at fault.
PS i dont think he checked his mirror, I think he only signalled.

So who's fault is this, and how would the dispute go?