Glazes, shades and washes can be made from any of the common hobby paints with the right additives, so if you get yourself some matt medium, drying retarder and flow aid you can make any colour do any of those things.
If you're not totally set on P3,
This paint range compatibility chart on dakka shows you what colours from each range much up and roughly how closely. As you can see P3 is the outsider ; p I use mostly Vallejo and Minitaire and find them both great for a lot of reasons.
Cons of
GW paints: Priced the highest, tubs waste and damage paint, tubs hard to use with airbrush, glaze/shade etc ranges are unnecessary if you can use additives, they keep changing their range which harms stores and end users, their paint is no better than other popular ranges.
If you're interested in Vallejo I can link you to some discussions on why people prefer or dislike them from here on dakka, or you can search them up. Not sure if there are many on P3, you might have more luck on their forum.