brake disc wear

[Drunkenmassacre]

Time to pick your collective brains... Been told that my front brake disc is looking at the end of its serviceable life. I have no issue with that (other than the cost of a new one) but my question is how can you tell if its worn? I can't see any indicators for wear and haven't got my Haynes manual to hand. Any ideas? Thanks.

Btw its a varadero xl 125 v3

 

[Drunkenmassacre]

errr just over 11k on the bike. Its funny, there's a slight lip on the rear but not the front. Suppose I'l find out when I take it for MOT.

Cheers guys