Thanks everyone for your feedback!
I live in Melbourne, Australia. I can't think of a single free service here :-( Wheel alignments here average around $50 to $75.
Finally got it looked at though. My local tyre and wheel shop said that because the wear wasn't consistent through the tyre, it was unlikely to be the result of a toe misalignment. It was patchy in my case and was put down to cornering, probably through roundabouts.
The wear wasn't enough to warrant a tyre rotation. But I did get an alignment + report done just for peace of mind. Report is attached here for anyone who is interested:
