I've got photographic evidence of the scene, however, liability....if it was my fault, why didn't he report it?
You may be up against it then mate.
I had similar a few years ago.
I was waiting at the head of a line of traffic on a side road, waiting to join a busy dual carriageway.
Eventually a gap came, and I started to drive out. As I did so the car behind me started out & tried to make for the same gap by pushing between me & the footpath. First I knew about it was when my car jumped sideways and stopped.
She had wedged her Saab in thoroughly, smashing her front right wing/headlight & the corner of the bumper. My rear wing was heavily stoved in.
Neither cars were going anywhere, so I exited mine and (whilst taking pictures with my phone) politely enquired if I could have her insurance details.
Long story short (yes, this is considerably abbreviated) when it came the claim she denied responsibility.! Her assertion was that I was filtering out into the right lane, and she was going into the left until I changed my mind & hit her.!
Despite my pointing out that as we were entering from a single carriageway, and that I could only ever join the left lane (and thereafter change lanes, if viable).
Despite my many photos clearly showing the cars wedged together, still on the single lane side road.
Despite all, that the insurance company said it was her word against mine, and settled "knock for knock".
I was furious and argued against it for many months. Got me nowhere, just squandered my time and made me upset and bitter..
Fwiw there is a slight Karma to the tale..
About 2 years later I was at a function and spotted the same young lady also arriving,,,, in a new Kia Picanto. The person I was talking to must have noticed that my attention was caught , and asked me if I knew ********.?
Not wanting to create any ill feeling I answered "No, only met her once but then she had a big flash Saab wearing that same personalised number plate.. "
"Oh, she's had to get that because it's all she can insure since she got her licence back". Turns out she had been banned for multiple drink-drive offences (got into a habit of liquid lunches).