Just spent over an hour chatting to DS1's lovely speech therapist (we see her approx every 3 to 4 months when she gives advice). She has agreed to refer him onto the head honcho for further assessment and to try and decide how to help him. She's stumped by him, understood totally why I was feeling out of my depth, and understood that he needs more input from speech and language!
Success! I was gearing up to write letters to the speech therapy service demanding more input, and it looks as if I may not have to. Could be one less battle to fight. Phew. He should be seen before September......