Another driver hit my car trying to turn right from the left lane of a roundabout, refuses to admit fault.

Driving home from Wales over the weekend, whilst going around a roundabout on the A487 near Caernarfon, another motorist decided they wanted to take the final exit from the left hand lane, and in turn hit the rear near side door/back wing of my car as I was taking the straight ahead exit from the outside lane (dual carriageway). The other motorist is refusing to admit fault as she feels that having her right indicator on gave her the right to cut across the roundabout. I’ve been quoted ~£2500 for the repair to my car. What is the best course of action for me to take?