Sher, make as much fuss as you can. Shout loud and long. Bombard your G.P. Write to the newspapers. Local and national. Lobby your M.P. Contact the school he will attend (if you know it) now, so that his needs can be accommodated well in advance. Advertise for any other parents with similar problems locally. If there are others, form a working group. I am sure you will have thought of all these options. Take a deep breath and fight.
Do you have the time and resources to train as a speech therapist yourself?
I know that they are in short supply.
Best wishes.