Well if you are looking to getting into wildlife and sports photography, it would always be best to get the longest and fastest lens you can afford. I think that 200mm would be a bit short for wildlife, I am ordering a 2x TC for my 120-300mm just for that extra reach. I don't do sports but having an f/2.8 tele sure helps with low light situations, and not only for that.
You should consider the weight of the lens aswell. Carrying a heavy lens on long walks can be tiring. The extra purchases you'll need to make should also be considered. After buying my long tele, I had to spend more money on a more sturdy tripod, a new ball & socket head, thinking of buying a good monopod, not to mention the cost of a good 105mm filter. If the UV filter was reaching £100 I don't even want to check for the price of a good polariser.
Why not looking into the Sigma 100-300mm F/4 aswell. It's cheaper and really sharp. But my suggestion would be to go for an f/2.8 lens. You can always step it down for sharper results but being able to shoot at f/2.8 is a must, especially for sports.