MetalMummy - welcome
My DS had/has? verbal dyspraxia and at 2.5 had the same gloomy outlook as you have been given.
His speech was severely disordered but he had excellent understanding and was using expressive language appropriately (it was just not easy to understand).
We paid for private SALT sessions, which started at 2.5 (this is very young, but he was very co-operative, you may need to wait some time yet to start if he does not have a reasonable concentration span). The sessions were all game based, and he saw them just as a chance to play games and have fun with the SALT.
We were told at that time that it was unlikely that he would be able to be taught in a main stream setting and that it would be worth looking at a local private school which specialises in dyspraxia and dyslexia.
I think it is fair to say that early intevension with SALT changed this outcome dramatically. He is now 6yo, has near normal speech, and has been taught in mainstream since he was 4yo. The improvement in his speech between 2.5 and 4 was considerable!
One of the things I would do for now, until you decide how to progress with SALT, is to google for the Mr Tongue exercises. Go through the routine twice a day, and you should see some rapid increase in the mobility of his tongue - this will help enormously with getting the right placement of the tongue once he starts the SALT.
I really hope you can afford to go privately, as the NHS provision so far for my DS has been 6 weeks SALT when he was 4yo and 6 weeks late last year! He would still be largely untreated if that was all we had available to us!
There are some good US sites on this topic - but they call it aspraxi (sp?) over there.
Good luck!