Hi mate,
Welcome to the forums.
There is no real way to tell if yours has had the uprated timing chain kit fitted. The only real way to tell is to actually check the chain and oil jet, in which case you may as well change them. As yours is a Vectra B it will most likely have the smaller oil jet fitted which lubricates the timing chain. There is a list of engine numbers affected from Vauxhall themselves. However, this list does not appear to be correct or too trustworthy from what I have read. The best advice I can give mate is get it changed with an uprated timing chain kit. Costs £141 from Vauxhall, that includes the VAT. From what I have read the fault appears to pop up around 60,000 to 70,000 miles. There are some forum members on here who can do the job for alot cheaper than most garages.
The part number you want for the uprated Timing chain kit from Vauxhall (with larger diameter oil jet) is 12577385
Hope this helps a bit mate.