Sorry Skyline Chick, the completing a turn thing is rubbish, but the rest is right.
If you were both coming from "give way" or "stop" signs, then the person going straight would have right of way.
But it appears the other bloke probably didn't have a give way/stop sign, which means he was already in the carriageway, which means you should've given way to him.
It's a tricky situation, but one way you can minimise the risk (a trick learned from years riding a motorbike) is to make eye contact with the other driver.
If you know he's seen you, you'll both be more cautious of each other & hopefully have time to stop if you need to.
good luck with the insurance.