I agree with Vocky, if you do have the earlier chain kit fitted there's nothing to say it will snap. I had my chain changed last year for peace of mind and there was no rattling. When it was being done it was found i had the earlier chain and nozzle fitted. My car had around 115k on the clock at the time so a lot more than your zafira. Regular oil and filter changes help a lot but won't stop it completey.
If you can afford it i'd recommend getting it changed, there is a guy on here called Benny based in Wolverhampton who changes the chain for around the £250 mark. if thats local to you it might be an option.
oh and welcome to the site 😃