Don't use instant coffee. It's designed to dissolve in water, so all it will do in a coffee maker is dissolve as the water goes through it. You may just as well make a batch of instant straight into the jug.
As for which coffee to buy, well, it's really a matter of taste. Have a look in somewhere like Tesco or Sainsbury's and read the labels for something that sounds like the sort of thing you like, and give it a try. Try to experiment with one or two brands and types to see what you prefer.
Also, when you make it, it's OK to use slightly less coffee cup than the directions say. I love a strong, Columbian coffee, but if use the quantities suggested in either the packet or in my cafetiere, then it comes out too strong even for me.