If my horse has a paddle on the front left leg, will this affect the score im given by a judge in any comp?

Because he paddles he won't do well in hunters, and possibly dressage, but it won't have any effect on his score in jumpers, as form isn't judged at all. You can try taking him to a dressage schooling show and see what comments the judge leaves for you, if any, about the way he paddles his leg, and even ask a dressage judge, should you get the chance, and if that is OK, then you can event him as well.