Josey
You will make beer with what you have, your beer would be better with a better yeast or even more of the same yeast.
The yeast Coopers supply is (if gossip is worth anything) a blend of Windsor and Mauri Ale 514.
Without getting too technical, when you add yeast it spends some time getting used to its new environment, then reproduces like crazy until it runs out of something it needs to reproduce (usually Oxygen) then it starts making Alcohol...
If you start with more yeast it gets up and running faster, this is good (up to a point) it takes yeast over 90 minutes (average about 2 hours) to make a new generation. Some of the bugs that can infect beer can reproduce every 20 minutes or so.
By the time the yeast is ready to get down to fermenting the beer, any bugs have had a chance to get going to and get going a lot faster (one of the reasons brewers are such head cases about cleaning and sterilising).
If you add more yeast at the start, it will get to work sooner what we call "out competing" the bugs. Most of the bugs cant reproduce if there is no Oxygen, then then the yeast makes Alcohol, alcohol kills most bugs yeast is conducting chemical warfare against the bugs.
Lots of other things affect how good your beer will taste, but the right amount of yeast is a big one, but the temperature you brew at, how clean your equipment is, well its a long list, will all play a part.
Not much point in adding more yeast now, the yeast already in there will have used up all the Oxygen, so the new yeast wouldn't be able to reproduce (well not much). Better to look for an extra packet or two of Coopers yeast, or even one of the many high quality packets available at any decent home brew shop, US-05, S-04, Nottingham are probably the most popular and all well worth a try in your next brew.
Welcome aboard - brewing can be a fascinating, even addictive hobby
Mark