Its very hard to see if its "stretched" its a chain. Using the inspection panel on the side of the engine cover to inspect the tensioner and how much is left will be the only real way to check. (Seek advice from a reputable garage I would)
I had mine inspected as i had a few rattles to sort on start up and tick over....turned out to be the vtc control gear on the end of the inlet camshaft that was at fault. Tom at TGM said my chain had to come off to replace the worn part, and in inspection also said that the chain was still within factory tolerances.....140k miles later.!
I purely had it changed as he and I both agreed to put on old when ot was all coming off anyway was abit backwards thinking, so i went and had new fitted. Providing its well maintained you shouldn't have any issues, my advice would be to get a garage who know these cars to check tolerances etc and advise any action and go from there.
Any "stretch" that has occurred should be taken up in the tensioner so lifting the cam cover and having a prod and wiggle may not show any significant signs.... but that inspection cover I explained about above is a bit of a bar stuard to get to.
Good luck