How to make sure I get the right headlamp units.

Hi
Before knowing anything about insignias I bought a 2013 Insignia Sports Tourer Elite Nav 2.0 CDTI Estate. It was registered in June 2013.
I got it cheap because it had front end damage that had been repaired. What I didn't know is that the original headlamp units (yes, xenon) have been replaced with halogen. Looking at the relative prices I can see why - but apart from not being able to see very well on the dark unlit country roads round here, it won't pass an MOT next time. However apart from that it's a really lovely car and I'm determined to get it back to how it should be - it's only got about 60,000 on the clock and is in really good condition.
So, I'm looking at ebay/breakers but am nervous about getting the right part.
Newbie questions - does the replacement have to come from an estate or are all the elite lamps identical? Do the 2013 onwards insignias have the same lamps as the my model? (Am I even understanding the pre/post 2013 difference correctly?)
Is there anything I should know about sourcing and replacing them?

Many thanks in advance
GAP