Are you on the birth certificate? If you are, then you have parental responsibilty and have just as much right to see your son as she does. I beleive they changed all this 2 years ago. Go and see a solicitor straight away. Looks like shes using your son to get at you.
Unfortunatly, I hear of this sort of thing all the time. Keep with it, try and be patient and let the courts do their work. I cant see any reason for them to turn you down. It may help your case if you payed his mother some money each week for his upkeep. This will look in court. Also, keep written logs of every kind of contact you have with his mother.
Good luck mate, I wish you and your son all the very best