Hi my DS has/had verbal dyspraxia and although he started SALT a little earlier than your DD, he has made remarkable progress. He now has almost normal sounding speech, although there are still a few odd vowel sounds still there.
I see that total chaos has given you the links I would have done, had I got there first
I would also advise you to try and get hold of a copy of the Mr Tongue exercises (I will have a little google and see if I can find a link once the children are in bed, but your SALT should be able to get you a copy if not). Done regularly, these help improve the child's control over the movements of the tongue which can be a big part of the condition.
Try to get a routine going each day for 10mins or so, to practice the SALT exercises you will get to do with your child. Being ruthless about practice is difficult, but it will make a huge difference to the outcome if done regularly. Almost all of the exercises we did were game based and great fun to do, so it shouldn't be too much of a chore
The frustration is good imo, it is what will spur her on to want to practice as she gets older and more aware - but managing it a little in the short term is good also.
I worried enormously that DS would end up being bullied, or teased over his speech once he started school - but you know - not once has any child even commented on it!