Buy a tin, spray a bit of card or scrap metal and hold it next to the car. Panther black is panther black though, unless your car's had a full respray in another black that hasn't been noted anywhere for reference. The other thing to bear in mind is that most car colours have more than one variant, but unless you send a part of the car away (i.e tow eye or fuel cap) to the likes of Dingbro, or give the car over to a bodyshop, there is a real chance any paint you buy will look different to what is on the car. Also worth considering the paint/lacquer is over a decade old which in itself has the potential to cause a difference against new paint. Unsure what you are hoping to paint with rattle cans but i can say from experience that's the spray pattern on the Halfords ones are small and circular, not great for doing larger or flat areas as tiger stripes are almost unavoidable, as is dry spray/orange peel. Lacquer in a can isn't much better to be honest as the pressure in the cans, IMO, isn't sufficient to produce an decent quality spray.
But that's just my opinion and it really depends on how picky you are being with the quality of finish.