Hi,
So I noticed a rubbing noise from the brake whilst riding home from work this evening and when I got to my garage I put her up on the paddock stands and noticed the front right disc is clearly warped.
Can I change just the one disc or do I have to replace both at once (to keep it balanced or something...)?
Thanks.

 

You could change just the one.

It depends on how close the other one is to the service limit, and what shape your pads are in as far as my advice goes. If I had newer discs and newer pads, I'd only replace the one disc. If my pads were close to being done, and the other disc was close to the service limit, I'd change everything at once.

 

I'll change one for now and the other side after next pay day.
I'll change the pads now on both sides too, the warped disc has made the outer pad go very uneven.
This forum has helped me out a few times now, thank you very much.